ORAU TEAM

Dose Reconstruction

Project for NIOSH

 

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation

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Document Title:

Rocky Flats Plant – Occupational Environmental 

Dose

Document Number: ORAUT-TKBS-0011-4 

Revision: 02 

Effective Date: 04/23/2007

Type of Document: TBD

Supersedes: Revision 01 

Subject Expert(s): Laura McDowell-Boyer and Craig A. Little

Site Expert(s): N/A

Approval: Signature on File Approval Date: 04/07/2007

Robert Meyer, Document Owner

Concurrence: Signature on File Concurrence Date: 04/04/2007

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 03/29/2007

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 04/16/2007

James P. Griffin, Deputy Project Director

Approval: Brant A. Ulsh Signature on File for Approval Date: 04/23/2007

James W. Neton, Associate Director for Science
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 2 of 62

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION

NUMBER DESCRIPTION

01/06/2004 00 New technical basis document for the Rocky Flats Plant –

Occupational Environmental Dose. Incorporates NIOSH and ORAU 

formal review comments. First approved issue. Initiated by Robert 

Meyer.

06/29/2004 01 Approved issue of Revision 01. NIOSH material added to 

Introduction; Table 4-1 columns corrected; Table 4-2 values 

corrected; page 50 table list change; Section B.2 3

H dose factor 

discussion added; page 52 table ID changed. Averaged two 1973 Pu 

and Am intake values to provide one annual estimate; changed FEIS 

reference citation on page 8, and corrected reference list for 2 

citations. Incorporates additional NIOSH formal review comments. 

Initiated by Robert Meyer.

04/23/2007 02 Approved Revision 02 initiated to update Section. 4.1.1 with standard 

NIOSH text, updated intakes to reflect site-wide maximum intakes 

which required obtaining location-specific model output as opposed 

to location-averaged output. Converted intake units to Bq, changed 

recommended AMAD to 0.3 μm for some years, clarified that 

resuspension was addressed in modeling. Added CDPHE data for 

1999–2005, other clarifications re SC&A comments. Attachment B 

updated to incorporate ICRP 68 organ dose factors. Worker 

Outreach comments pertaining to CT-0202 and CT-0208 have been 

addressed in a revision of Section 4.2.3. Revised to incorporate 

attribution per ORAU direction. Incorporates NIOSH formal review 

comments and an additional comment, changing recommendation of 

0.3 μm to 1.0 μm AMAD for certain years. Constitutes a total rewrite 

of document. This revision results in an increase in assigned dose 

and a PER is required. Training required: As determined by the 

Task Manager. Initiated by Robert Meyer.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 3 of 62

TABLE OF CONTENTS

SECTION TITLE

Acronyms and Abbreviations ...............................................................................................................

PAGE

6

4.1 Introduction ..............................................................................................................................8

4.1.1 Purpose........................................................................................................................9

4.1.2 Scope...........................................................................................................................9

4.2 Internal Dose from Onsite Atmospheric Radionuclide Concentrations...................................... 9

4.2.1 Radionuclides of Concern.............................................................................................9

4.2.2 Source Terms.............................................................................................................10

4.2.2.1 Operational Period (Pre-1993) Source Terms .............................................. 10

4.2.2.2 Post-Operational Period (Post-1992) Source Terms .................................... 11

4.2.3 Annual Intake of Radioactivity.....................................................................................11

4.3 External Exposure to Onsite Atmospheric Radionuclide Concentrations ................................ 16

4.3.1 Radionuclides of Concern...........................................................................................16

4.3.2 Exposure Rates..........................................................................................................16

4.4 Uncertainty.............................................................................................................................19

4.4.1 Uncertainty in Internal Exposure Estimates ................................................................19

4.4.1.1 Intakes Estimated for 1953 to 1964.............................................................. 19

4.4.1.2 Intakes Estimated for 1965 to Present.......................................................... 20

4.4.2 Uncertainties in External Dose Estimate.....................................................................20

4.5 Attributions and Annotations .................................................................................................. 20

References ........................................................................................................................................24

Glossary ............................................................................................................................................31

ATTACHMENT A, ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS AT THE

 ROCKY FLATS PLANT........................................................................................ 33

A.1 Introduction ...........................................................................................................................34

A.2 Measurement of Total Long-Lived Alpha Activity and Plutonium in Air ................................... 34

A.3 Atmospheric Transport Modeling............................................................................................ 36

ATTACHMENT B, SCREENING OF RADIONUCLIDE SOURCE TERMS FOR

 ENVIRONMENTAL DOSE EVALUATION ........................................................... 55

B.1 Screening Methodology ........................................................................................................ 56

B.2 Tritium....................................................................................................................................56
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 4 of 62

B.3 Depleted and Enriched Uranium ............................................................................................ 57

B.4 Americium-241.......................................................................................................................58

LIST OF TABLES

TABLE TITLE

4-1 Isotopic composition of RFP plutonium ..................................................................................

PAGE

10

4-2 Site-wide maximum annual median inhalation intakes of 239,240Pu and 

241Am for 1953 to 1964, based on atmospheric modeling....................................................... 13

4-3 Site-wide maximum annual median inhalation intake of 239,240Pu and 

241Am (1965 to 2005), based on monitoring data.................................................................... 14

4-4 External gamma radiation ...................................................................................................... 18

A-1 Monthly average concentrations of total long-lived alpha activity in onsite 

air samples, October 1964 to December 1971 ....................................................................... 47

A-2 Estimated annual average concentrations of 239,240Pu in onsite air samples 

between 1965 and 1994 based on measurement data provided in Table 

A-1, RFP annual environmental reports, RFETS monthly and quarterly 

monitoring reports, and CDPHE quarterly environmental surveillance 

reports....................................................................................................................................50

A-3 Annual average concentrations of plutonium in air for three location 

groups, RFP contractor monitoring, 1971 to 1990)................................................................. 51

A-4 Data from Table III-4 in Rope et al. (1999) showing a comparison of 

239,240Pu concentrations in onsite and offsite air, measured by CDPHE .................................. 52

A-5 Data from Table B-14 in Rope et al. (1999) showing annual average 

concentrations of 239,240Pu in Denver air, 1971 to 1989........................................................... 53

A-6 Corrected annual average concentrations of 239,240Pu in air at perimeter 

monitoring stations.................................................................................................................54

B-1 Maximum estimated committed doses for tritium by year ....................................................... 59

B-2 Maximum estimated committed doses for depleted uranium, by year..................................... 60

B-3 Maximum estimated committed doses for enriched uranium by year ..................................... 61

B-4 Maximum estimated committed doses for 241Am by year........................................................ 62
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 5 of 62

LIST OF FIGURES

FIGURE TITLE

4-1 Grid map used in atmospheric modeling, showing locations of six 

computational nodes representing the RFP Industrial Area....................................................

PAGE

13

4-2 External dose at RFP as a function of year ............................................................................ 17

A-1 Location of samplers operated by RFP contractor.................................................................. 40

A-2 Location of onsite computational nodes used to predict average onsite air 

concentrations for RFP industrial area ................................................................................... 41

A-3 Annual average 239,240Pu concentrations in air as a function of time for 

particles < 30-μm AED in RFP industrial area ........................................................................ 42

A-4 Annual average 239,240Pu concentrations in air as a function of time for 

particles < 30-μm AED in the perimeter area surrounding RFP.............................................. 43

A-5 Locations of computational nodes used to compute annual average 

perimeter concentrations shown in Figure A-6 ....................................................................... 44

A-6 Eastern part of RFP industrial area, showing locations of CDPHE air 

monitoring stations D-1 to D-5 ................................................................................................ 45

A-7 Locations of offsite air samplers in 1975 ................................................................................ 46
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 6 of 62

ACRONYMS AND ABBREVIATIONS

AED aerodynamic equivalent diameter

AMAD activity median aerodynamic diameter

Bq becquerel

CDPHE Colorado Department of Public Health and Environment (previously Colorado 

Department of Health)

Ci curie

CL confidence limit

DOE U.S. Department of Energy

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

EPA U.S. Environmental Protection Agency

ET extrathoracic

fCi femtocurie

ft foot

FGR Federal Guidance Report

g gram

GEP good engineering practice

GM geometric mean

HEPA high-energy particulate air

hr hour

ICRP International Commission on Radiological Protection

m meter

mCi millicurie

mi mile

mrem millirem

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

pCi picocurie

POC probability of causation

RAC Risk Assessment Corporation

RATCHET Regional Atmospheric Transport Code for Hanford Environmental Tracking

RFETS Rocky Flats Environmental Technology Site

RFP Rocky Flats Plant

TBD technical basis document

TLD thermoluminescent dosimeter

TLLα total long-lived alpha
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 7 of 62

U.S.C. United States Code

wk week

yr year

α alpha particle

μm micrometer

σ sigma

§ section or sections
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 8 of 62

4.1 INTRODUCTION

Technical basis documents and site profile documents are not official determinations made by the 

National Institute for Occupational Safety and Health (NIOSH) but are rather general working 

documents that provide historic background information and guidance to assist in the preparation of 

dose reconstructions at particular sites or categories of sites. They will be revised in the event 

additional relevant information is obtained about the affected site(s). These documents may be used 

to assist NIOSH staff in the completion of the individual work required for each dose reconstruction.

In this document the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

EEOICPA defines a DOE facility as “any building, structure, or premise, including the grounds upon 

which such building, structure, or premise is located ... in which operations are, or have been, 

conducted by, or on behalf of, the Department of Energy (except for buildings, structures, premises, 

grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program)” [42 U.S.C. § 

7384l(12)]. Accordingly, except for the exclusion for the Naval Nuclear Propulsion Program noted 

above, any facility that performs or performed DOE operations of any nature whatsoever is a DOE 

facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only determines 

eligibility for a dose reconstruction, which is a prerequisite to a compensation decision (except for 

members of the Special Exposure Cohort). The compensation decision for cancer claimants is based 

on a section of the statute entitled “Exposure in the Performance of Duty.” That provision [42 U.S.C. § 

7384n(b)] says that an individual with cancer “shall be determined to have sustained that cancer in the 

performance of duty for purposes of the compensation program if, and only if, the cancer ... was at 

least as likely as not related to employment at the facility [where the employee worked], as 

determined in accordance with the POC [probability of causation1

As noted above, the statute includes a definition of a DOE facility that excludes “buildings, structures, 

premises, grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 

(42 U.S.C. 7158 note), pertaining to the Naval Nuclear Propulsion Program” [42 U.S.C. § 7384l(12)]. 

While this definition contains an exclusion with respect to the Naval Nuclear Propulsion Program, the 

section of EEOICPA that deals with the compensation decision for covered employees with cancer 

[i.e., 42 U.S.C. § 7384n(b), entitled “Exposure in the Performance of Duty”] does not contain such an 

exclusion. Therefore, the statute requires NIOSH to include all occupationally derived radiation 

exposures at covered facilities in its dose reconstructions for employees at DOE facilities, including 

radiation exposures related to the Naval Nuclear Propulsion Program. As a result, all internal and 

external dosimetry monitoring results are considered valid for use in dose reconstruction. No efforts 

are made to determine the eligibility of any fraction of total measured exposure for inclusion in dose 

reconstruction. NIOSH, however, does not consider the following exposures to be occupationally 

derived:

] guidelines established under 

subsection (c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the probability of causation

guidelines (nor the dose reconstruction regulation) define “performance of duty” for DOE employees 

with a covered cancer or restrict the “duty” to nuclear weapons work.

• Radiation from naturally occurring radon present in conventional structures

• Radiation from diagnostic X-rays received in the treatment of work-related injuries

 

1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC. 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 9 of 62

4.1.1 

The preparation of this report used available information about the Rocky Flats Plant (RFP) 

environment dating back to 1952. The user is strongly advised to consider the remarks in the text on 

appropriate use and interpretation of the material.

Purpose

Occupational environmental dose refers to the radiation dose received in the course of work duties 

outside Plant buildings but on the RFP site. Internal and external exposures to radionuclides in the 

outdoor environment are considered separately here in calculating this dose. Estimated occupational 

environmental dose can be utilized when a worker did not have the potential for routine exposures.

4.1.2 

Section 4.2 presents information necessary to estimate internal environmental dose. It identifies the 

radionuclides of concern. Screening the list of radionuclides relied on work done for the Historical 

Public Exposure Studies on Rocky Flats (ChemRisk 1994a; Rood and Grogan 1999). Section 4.2 

discusses the resulting source terms (release rates) for radionuclides considered potentially 

significant to internal environmental dose and provides estimated annual inhalation intake activities of 

radionuclides.

Scope

Section 4.3 contains information necessary for estimating external environmental dose. Ambient 

doses, taken from annual environmental reports for RFP published from 1975 through 1995, were 

developed for the site. The reports summarize external dose as measured by thermoluminescent 

dosimeters (TLDs) at the Plant, its general environs, and selected nearby communities. 

Section 4.4 considers uncertainties in the information provided for estimating occupational 

environmental dose. The discussion addresses sources of uncertainty and provides quantitative 

information where possible. 

4.2 INTERNAL DOSE FROM ONSITE ATMOSPHERIC RADIONUCLIDE 

CONCENTRATIONS

4.2.1 

The Historical Public Exposures Studies on Rocky Flats were conducted in the 1990s as part of a 

1989 Agreement in Principle between DOE and the State of Colorado to identify potential health 

effects in nearby communities exposed to past releases. Phase I and Phase II of the studies provided 

comprehensive analyses of releases of radionuclides from RFP during the period from 1953 to 1989, 

although component assembly operations actually began in 1952 and all production operations 

formally ceased in 1992 (ChemRisk 1992, 1994a; Voillequé 1999a,b,c; Weber et al. 1999). 

Radionuclides of Concern

The Phase I study identified several radionuclides as potentially significant releases – 3H, natural 

thorium, enriched and depleted uranium, 239/240Pu, 241Pu, and 241Am. The results of the Phase I study 

identified plutonium as the primary material of concern with respect to offsite exposures. The Phase II 

study focused the air pathway exposure assessment on the isotopes of plutonium. The potential 

importance of 3

H, enriched and depleted uranium, and 241Am to onsite exposures was reevaluated 

here to determine if previous determinations of insignificance were relevant for occupational 

exposures. Releases of natural thorium were difficult to quantify, but were probably insignificant 

based on a review of processes and ventilation filter use (ChemRisk 1994a, Task 5, p. 123).
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 10 of 62

To evaluate the potential significance of radionuclides other than isotopes of plutonium, an estimate 

was developed of committed inhalation dose from a 1-yr intake using airborne stack emission 

estimates from the Phase I study, the air dispersion modeling results from Phase II, an assumed 

inhalation rate of 2,400 m3

/yr (ICRP 1975), and dose factors from International Commission on 

Radiological Protection (ICRP) Publication 68 (ICRP 2001). Attachment A contains a summary of the 

atmospheric dispersion model. Attachment B discusses the methods and results of this screening 

evaluation. Briefly, the maximum organ dose due to inhalation [assuming an activity median 

aerodynamic diameter (AMAD) of 0.3 μm) in any given year since 1953 for any of these radionuclides 

was estimated to be that for 241Am, on the order of 34 mrem for the stack releases. The maximum 

predicted committed doses for 3

H, depleted uranium, and enriched uranium for a 1-yr intake were 

0.06 mrem, 1.2 mrem, and 0.65 mrem, respectively. The Phase I study estimated that 241Am is 

potentially present in excess of 0.23 times the alpha activity of 239,240Pu in the 903 Area due to 

ingrowth of 241Am from 241Pu in the cutting oil stored in that area and in soils contaminated with the 

cutting oil (ChemRisk 1994b, Appendix H). Therefore, 241Am associated with soil resuspended from 

the 903 Area or emitted with plutonium isotopes from stacks was considered a contributor to dose. 

Stack releases of 3

H and the uranium isotopes were excluded as potentially significant contributors 

(Attachment B).

The Final Environmental Impact Statement for the Rocky Flats Plant (DOE 1980) indicates an isotopic 

composition of plutonium by weight as follows:

Table 4-1. Isotopic composition of RFP 

plutonium.

Isotope

Percent 

by weight

Percent of Pu 

alpha activitya

Pu-238 0.01 2.33

Pu-239 93.79 79.62

Pu-240 5.80 18.04

Pu-241 0.36 (beta emitter)

Pu-242 0.03 0.00161

a. From ChemRisk (1994a, p. 105, Table 2-34).

As indicated in the table, 238Pu and 242Pu are minor contributors to the alpha activity of plutonium 

expected in the RFP environment [1]. Thus, the following sections report source terms and intakes for 

239,240Pu and 241Am only.

4.2.2 

The discussion of atmospheric source terms for 239,240Pu and 241Am released to the RFP environment 

addresses two periods: the operational, or pre-1993, period, when production activities were ongoing, 

and the post-1992 period, when production activities had ceased and releases were more likely to 

occur as a result of past contamination or decontamination and decommissioning activities.

Source Terms

4.2.2.1 Operational Period (Pre-1993) Source Terms

In 1952, the only operational activities that took place at RFP were in Building 991 (Putzier 1982), in

which components manufactured at other locations were assembled (ChemRisk 1992). No significant 

emissions are estimated to have occurred during this year. From 1953 through part of 1992, 

fabrication and recycling activities at RFP resulted in radionuclide releases to the onsite atmospheric 

environment as a result of “routine” operations (continuous releases), and “nonroutine incidents” 

(discrete events). The term “routine” was used in the Radiological Assessments Corporation (RAC) 

Phase II dose reconstruction reports to distinguish continuous releases from the release spikes that 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 11 of 62

occurred during the 1957 and 1969 fires and during 903 Area high-wind events. However, routine 

releases “included discharges that were due to a variety of unplanned events and conditions that 

arose during facility operations,” including “small fires involving plutonium metal,” the “peroxide tank 

explosion in Building 771 in 1957 and the glovebox drain fire in Building 776 in 1965,” among other 

events (Voillequé 1999c).

The most significant discrete release occurred during and shortly after September 11, 1957. A 

glovebox fire in Building 71 (now called Building 771) resulted in a release of plutonium estimated at 

21 Ci (50th-percentile estimate; Voillequé 1999a). The next most significant discrete release location 

was the 903 Drum Storage Area (also called the 903 Pad or 903 Area). An estimated 3.1 Ci 

(50th percentile) of plutonium (<30-μm size fraction) were released from the 903 Pad over several 

years, mainly as a result of mechanical disturbance and wind action (Weber et al. 1999). This 

estimate consists of the 24-hr integrated release quantities for 24 identified discrete events during the 

1964-to-1969 period. An asphalt pad placed over the area in 1970 decreased the source term 

dramatically, although resuspension of downwind contaminated soil continued to disperse plutonium 

to the air in later years. The third most significant nonroutine contaminant release occurred during the 

May 11, 1969, fire, when approximately 0.037 Ci (37 mCi) of plutonium were released from the 

Building 779 stack (Voillequé 1999b). 

Total routine (non-discrete-event) plutonium emissions from 1953 to 1989 are estimated to be on the 

order of 0.12 Ci (Voillequé 1999c). This estimate does not include releases due to resuspension of 

contaminated soil downwind of the 903 Pad or resuspension of contaminated soil in other areas of the 

Plant due to deposition from the primary sources. Although the release of plutonium due to 

resuspension is not included in this estimate of routine emissions, it is addressed in this TBD as a 

contributor to exposure.

4.2.2.2 Post-Operational Period (Post-1992) Source Terms

After 1992, production operations at RFP officially ceased. However, source terms of plutonium to the 

environment could still exist due to contaminated soils. Air monitoring continues to be carried out by 

the RFP contractor and the Colorado Department of Public Health and Environment (CDPHE). 

Average and maximum annual median ambient concentrations have not been observed to increase 

since operations ceased, despite the decommissioning activities that have taken place over the last 

12 yr (Table A-2, Attachment A).

4.2.3 

To calculate intake of 239,240Pu and 241Am, the estimated site-wide maximum annual median [2] air 

concentrations of these isotopes in the RFP environment were multiplied by an annual inhalation rate. 

The assumed intake rate was 2,400 m3

/yr (ICRP 1975), corresponding to an hourly rate of 1.2 m3, for 

light activity and a 2,000-hr work year. Intake can be scaled for increased inhalation rates or other 

than 2,000 hr of exposure.

Annual Intake of Radioactivity

Air concentrations of 239,240Pu and 241Am were estimated as described in Attachment A. Onsite air 

monitoring data are the preferred source of air concentrations (see Attachment A) for 239,240Pu, but in 

the early years (until 1964) such data were not sufficiently descriptive or complete to allow reliable 

estimates. Thus, dispersion modeling results were used to estimate air concentrations of 239,240Pu for 

these years. During these early years, stack or building vent emissions were the main source of 

plutonium to onsite air, and measurements of these releases are available. Resuspension of 

previously deposited isotopes also contributed to onsite air concentrations. The model used 

(described in Attachment A) addressed contributions from the primary sources identified in the 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 12 of 62

Phase I study (ChemRisk 1992, 1994a) as well as resuspension. The ratios of 241Am activity to 

239/240Pu activity in effluents were not measured until the 1980s; however, between 1985 and 1989, 

this ratio averaged 0.22 (ChemRisk 1994a). This ratio likely overestimates the fractional release in 

earlier years, when less 241Am had grown in to the plutonium available for processing Therefore, this 

ratio of 0.22 is used to estimate 241Am concentrations from 1953 to 1964. 

After 1964, suspension or resuspension (Rood and Grogan 1999, p. 57) of contaminated soil was the 

main source of plutonium to onsite air. Air monitoring data provided either total long-lived alpha 

(TLLα) concentrations, from which 239,240Pu values could be derived, or actual measurements of 

239,240Pu. The annual environmental reports (Dow 1972a, 1973 to 1976; Rockwell 1977 to 1989; 

EG&G 1989 to 1993; Kaiser-Hill 1994) were useful in providing summaries of air concentrations by 

sampler location based on monthly reporting through 1994. After 1994, Rocky Flats Environmental 

Technology Site (RFETS) monitoring reports and the CDPHE monitoring reports provided quarterly 

summaries of monitoring results. Activity concentrations of 241Am are estimated after 1964 by 

assuming that the concentration of 241Am is 30% of the 239,240Pu concentration based on 

measurements of the 241Am/239Pu activity in RFP soil by two separate researchers in the 1970s (Poet 

and Martell 1972; Krey et al. 1976) and more recently by Litaor and Allen (1996). This assumption is 

favorable to claimants because the average measured activity ratios in soil were found to be less than 

0.20 by these three groups of researchers [3]. 

Table 4-2 lists estimated annual intakes of 239,240Pu between 1953 and 1964, based on the 

atmospheric modeling [4] described in Attachment A. The values are expressed in becquerels per 

year. The calculated intakes represent a maximum annual median (50th percentile) of the six 

computational nodes evaluated in the RFP industrial area for 500 Monte Carlo model realizations 

simulated for each year, and are exclusive of the buffer zone (Figure 4-2). The location of the 

maximum concentrations was the north-central, northeast, or southeast node, which is expected 

based on the locations of the primary sources and the general west-to-east wind direction. The 

median intakes in Table 4-2 correspond to isotopes associated with particles smaller than 15-μm 

aerodynamic equivalent diameter (AED), which is an upper limit for respirable particles according to 

Rood and Grogan (1999, p. iv). 

Table 4-2 lists two results for 1957. Results for “1957” include the September 11 fire, which caused 

the annual intakes to be substantially higher than during the years before and after. If a worker was 

known to have been present during that year, and that individual might have been present in 

September, it is appropriate to use this value. The results for “1957, w/o fire” can be used for 

individuals who worked a partial year that did not include the month of September. Elevated releases 

of 239,240Pu and 241Am attributable to the 1957 fire occurred over several hours after the fire began at 

approximately 10:00 p.m. on September 11. Exposure to the direct releases would have occurred 

during that month (the air concentrations associated with soil-deposited 239,240Pu from the fire are 

included in both 1957 values by considering resuspension of contaminated soil in the dispersion 

modeling). 

Table 4-3 lists estimated annual intakes of 239,240Pu and 241Am between 1965 and 2002. The values 

for 239,240Pu in this table are based on site-wide maximum annual median measured concentrations at 

samplers across the site, and thus represent concentrations at the locations of higher concentration 

(typically near the 903 Area). Therefore, these values are inherently favorable to claimants when 

applied as an estimate of environmental exposure for the industrial area. The 239,240

Pu air 

concentrations supporting the intakes in Table 4-3 are described in Attachment A and summarized in 

Table A-2. Intakes were calculated from air concentrations by assuming a respirable fraction of 1.0, 

despite the reported values of this parameter ranging from 0.2 to 0.4 in a review of the subject in 

Rope et al. (1999, pp. III-79 to III-81). Low- and high-volume air samplers at RFP collected particles 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 13 of 62

Table 4-2. Site-wide maximum annual median 

inhalation intakes of 239,240Pu and 241Am for 1953 

to 1964, based on atmospheric modeling (AED 

<15 μm; assume respirable).a 

Year

Pu-239, 240

intake (Bq/yr)

Am-241 intake

(Bq/yr)

b 

1953 3.6E-05 7.8E-06

1954 1.7E-04 3.7E-05

1955 1.7E-04 3.6E-05

1956 5.5E-04 1.2E-04

1957 6.8E-02 1.5E-02

1957 w/o fire 2.1E-02 4.7E-03

1958 9.1E-03 2.0E-03

1959 8.1E-03 1.8E-03

1960 5.0E-03 1.1E-03

1961 2.9E-03 6.4E-04

1962 5.4E-03 1.2E-03

1963 1.4E-02 3.0E-03

1964 6.1E-02 1.3E-02

a. Atmospheric modeling described in Attachment A [4]. 

b. Am-241 intake is assumed to be 22% of the Pu-239/240 

intake (Section 4.2.3).

479000 479500 480000 480500 481000 481500 482000 482500 483000 483500 484000 484500 485000 485500 486000

UTM Coordinate East (m)

4413000

4413500

4414000

4414500

4415000

4415500

4416000

4416500

4417000

4417500

4418000

4418500

UTM Coordinate North (m)

N

W E

S

128

Buffer zone boundary

Plant exclusion boundary

Woman Creek

North Walnut Creek

Industrial Area

Figure 4-1. Grid map used in atmospheric modeling, showing locations of six 

computational nodes representing the RFP Industrial Area [4]. 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 14 of 62

Table 4-3. Site-wide maximum annual median inhalation intake of 239,240Pu and 241Am (1965 to 2005), 

based on monitoring data (respirable fraction of sampled particles = 1.0). 

Year

Pu-239, 240

intake (Bq/yr)a

Am-241 intake 

(Bq/yr)b

1965 1.8E-01 5.5E-02

1966 3.3E-01 9.8E-02

1967 1.1E+00 3.3E-01

1968 3.4E+00 1.0E+00

1969 5.9E+00 1.8E+00

1970 2.9E-01 8.6E-02

1971 3.3E-01 1.0E-01

1972 3.4E-01 1.0E-01

1973 4.7E-01 1.4E-01

1974 2.8E-01 8.4E-02

1975 8.6E-02 2.6E-02

1976 1.2E-01 3.6E-02

1977 5.3E-02 1.6E-02

1978 7.6E-02 2.3E-02

1979 4.4E-02 1.3E-02

1980 4.0E-02 1.2E-02

1981 4.9E-02 1.5E-02

1982 4.2E-02 1.3E-02

1983 3.8E-02 1.1E-02

1984 4.9E-02 1.5E-02

1985 3.6E-02 1.1E-02

Year

Pu-239, 240

intake (Bq/yr)a

Am-241 intake 

(Bq/yr)b

1986 4.1E-02 1.2E-02

1987 1.1E-01 3.3E-02

1988 6.3E-02 1.9E-02

1989 4.4E-02 1.3E-02

1990 8.4E-02 2.5E-02

1991 1.0E-01 3.1E-02

1992 5.1E-02 1.5E-02

1993 3.1E-02 9.4E-03

1994 3.6E-02 1.1E-02

1995 2.0E-02 5.9E-03

1996 7.3E-03 2.2E-03

1997 5.9E-03 1.8E-03

1998 1.1E-02 3.2E-03

1999 1.2E-02 3.5E-03

2000 1.3E-02 3.9E-03

2001 1.4E-02 4.2E-03

2002 4.5E-03 1.3E-03

2003 1.6E-02 4.8E-03

2004 2.4E-03 7.1E-04

2005 9.1E-03 2.7E-03

a. Calculated from air concentration data in Table A-2.

b. Calculated by multiplying 239,240Pu intake by 0.30 (see Section 4.2.3).

larger than respirable (Rope et al. 1999) to varying degrees as samplers were replaced over the 

years. Because the respirable fraction of sampled particles is not accurately known, a respirable 

fraction of 1.0, which is favorable to claimants, was assumed.

The values reported for 241Am in Table 4-3 (after 1970) were calculated by multiplying the 239,240Pu 

intake values by 0.30, in accordance with the rationale described above in this section. Again, a 

respirable fraction of 1.0, which is favorable to claimants, was assumed.

Annual intakes estimated in Tables 4-2 and 4-3 are based on a 2,400-m3

/yr inhalation rate, but can be 

scaled to a different rate. Furthermore, the values can be scaled for partial-year exposures, with the 

following cautionary note. For 1957, approximately 70% of the intake of 239,240Pu can be attributed to 

the September 11 fire. Thus, if a worker was present on the site for only a portion of 1957, but during 

September, the entire annual intake should be assumed. If a worker was present on the site in 1957, 

but not during September, the intake designated “1957 w/o fire” should be assumed, and scaling of 

this value for a partial-year exposure can be done.

The assumed solubility of inhaled 239,240Pu should consider the following information. Plutonium in 

metal-working operations and involved in fires is generally insoluble (type S or slowly transportable in 

the lungs), but can be highly insoluble (super type S). Exceptions, such as plutonium metal 

associated with solvents, might exist. Plutonium in chemical processing operations can be either 

soluble (type M or moderately transportable in the lungs) or insoluble. The solubility of plutonium 

should be selected based on what is most favorable to the claimant in light of the organ of interest [5]. 

The AMAD of airborne 239,240Pu and 241Am will vary according to the source and, thus, according to 

location on the Plant site. For routine releases from stacks and vents in which high-energy particulate 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 15 of 62

air (HEPA) filters are operating as designed, the particle size of stack-effluent particles has been 

reported to be on the order of 0.3 μm AMAD (Rood 1999; Grogan, Sinclair, and Voillequé 2000). The 

AMAD of particles released from the two larger fires (1957 and 1969) were not assessed, but there 

was evidence that the HEPA filtration systems did not remain intact throughout these events 

(Voillequé 1999a,b). A study of aerosols generated from another RFP fire involving plutonium and 

solvents indicated an mass median diameter on the order of 0.32 μm for this incident (Mann and 

Kirchner 1967), which correlates to an AMAD of approximately 1-μm, using the correlation provided 

by Hayden (1976) for RFP environmental plutonium and stack effluent air. However, the site-wide 

maximum intakes listed in Table 4-3 often reflect the air concentrations at the eastern edge of the site 

that resulted from suspension and resuspension of soil contaminated with 239,240Pu and 241Am from the 

903 Area. The AMAD of airborne particles containing plutonium in this area of RFP has been 

characterized as ranging from 2 to 7 μm (Grogan, Sinclair, and Voillequé 2000). Although the 

physical diameters of plutonium particles in soil were found to be on the order of 0.3- to 1-μm AMAD, 

it appears that the airborne plutonium particles in this area were attached to soil particles, resulting in 

an aerosol most appropriately characterized by an AMAD of ~5 μm (Grogan, Sinclair, and Voillequé

2000). 

Thus, the AMAD is a time-dependent as well as location-dependent attribute of airborne radionuclides 

at RFP. Unfortunately, the relative contributions of the various sources of airborne plutonium at 

specific outdoor work locations are not known. From Figure 2-5 and Table 2-D in ORAUT (2006a), it 

is clear that most of the work locations at RFP were upwind of the 903 Area plutonium source

because the predominant wind direction at RFP is from the northwest (Rockwell 1989). 

Measurements of soil concentrations of plutonium in 1988 surrounding RFP, at distances of 1 and 

2 mi from the center of the Plant, indicated dramatically larger concentrations east and southeast of 

the 903 Area than in other areas (Rockwell 1989). However, the degree to which the concentrations 

upwind of the 903 Area were influenced by resuspended plutonium is not known. Outdoor workers in 

the vicinity of the buildings from which routine releases occurred, and upwind of the 903 Area, could 

have been exposed to particulates with AMADs on the order of 0.3 μm, although resuspended 

particles would also be present at their location. The following recommendations are made based on 

the information given above. For intakes estimated prior to 1965 (Table 4-2), an AMAD of 1.0 μm 

should be assumed for airborne ambient 239,240Pu and 241Am, because worker intakes largely resulted 

from routine releases, the 1957 fire, and any resuspension of deposited 239,240Pu and 241Am that 

occurred in the worker’s vicinity . An AMAD of 1.0 μm should also be assumed for intakes occurring 

during 1965, 1966, and 1970 to 1993 [6]. The disturbance of the 903 Area as part of an attempt to 

remove leaking barrels, and subsequent high-wind events that served as the main dispersal 

mechanism for plutonium contaminating the soils of the 903 Area, occurred between 1967 and 1969. 

During 1967, 1968, and 1969, and after 1993, an AMAD of 5 μm should be assumed [7]. The sitewide maximum intakes from 1967 to 1969 (Table 4-3) are clearly dominated by the suspended 

plutonium that originated from the 903 Area before placement of the asphalt pad. After 1993, when 

production had ceased, resuspension of plutonium is the mostly likely source of airborne plutonium. 

The recommendation to assume an AMAD of 1.0 μm from 1970 through 1993 is based on the fact 

that air concentrations downwind of the 903 Area, which are better characterized by an AMAD of 5.0 

μm, tended to be only slightly (less than an order of magnitude) higher than other onsite areas, but not 

always. In 1972, the onsite airborne concentrations downwind of the 903 Area were 2 to 3 times 

higher than in other areas of RFP (Dow 1972b). However, in 1990 to 1992, the air concentrations in 

the main production areas of RFP (northern section of the industrial zone) exceeded those downwind 

of the 903 Area.

These assumptions are favorable to the claimant in the following respects: (1) for most organs, 

assuming an AMAD of 1.0 μm increases the dose by about a factor of 1.5 over the dose calculated by 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 16 of 62

assuming an AMAD of 5.0 μm; and (2) using the site-wide maximum intakes often implicitly assumes 

the worker is exposed to the air concentrations downwind of the 903 Area, which is not the location of 

most exposures. The ET airways dose factor is a factor of 1.5 times higher for the AMAD assumption 

of 5 μm (the particle size more appropriate for resuspended plutonium) versus 1.0 μm (1.5 ×10-5

Sv/Bq versus 9.5 ×10-6 Sv/Bq), and thus for cases in which that organ dose is of most interest, the 

AMAD of 5.0 μm should be assumed for all years. 

4.3 EXTERNAL EXPOSURE TO ONSITE ATMOSPHERIC RADIONUCLIDE 

CONCENTRATIONS

4.3.1 

As described in Section 4.2.1, 3

H, natural thorium, enriched and depleted uranium, 239/240Pu, 241Pu, 

and 241Am were identified as having been released to the air during the RFP operational period. 

However, because none of the isotopes of concern is a strong gamma emitter, there is little external 

dose. 

Radionuclides of Concern

4.3.2 

Prior to 1975, external exposure of workers was determined by the use of film badges, not TLDs (see 

ORAUT 2006b, Section 6.2). Film badges are not well suited to environmental monitoring, and 

environmental measurements prior to 1975 are not readily available. The determination concerning 

this lack of data is consistent with other site evaluations. Rope et al. (1999) pointed out that before

the early 1970s, environmental data were fewer and of lower quality than later data. In his review of 

RFP (covering 1952 to 1982), Putzier (1982) spent little time discussing external occupational 

exposure measurements and none describing outdoor measurements. This is largely because the 

concern regarding environmental exposures to workers or the public was centered on plutonium. 

Rope et al. (1999) described external gamma exposures, but the information is limited to an analysis 

of aerial survey data that target plutonium by measuring 241Am. 

Exposure Rates

Data that can be used to estimate external environmental dose exist in annual environmental reports 

for 1975 to 1994 (Dow 1972a, 1973 to 1976; Rockwell 1977 to 1989; EG&G 1989 to 1993; Kaiser-Hill 

1994). Gamma exposure rates were routinely measured at 12 to 15 locations on the site. Those data 

are plotted in Figure 4-2 for continuous exposures during a year (8,760 hr) and summarized in 

Table 4-4 for 2,500 hr/yr exposures. The locations of the monitoring stations were not available; 

however, a site-wide maximum value is estimated by adding the recommended standard deviation 

(described below), reflecting both spatial and temporal variation, to the site-wide mean value [8].

For the 19-yr period from 1975 to 1993, the number of independent measurements ranged from 87 to 

176 per year. Table 4-4 lists the reported means and standard deviations (2σ) of the measured 

samples for these years with the exception of 1977. For 1977, only the mean was reported. There is 

no explanation available for the relatively large standard deviations in 1975, 1976, and 1978. Due to 

this large variation in reported standard deviations, a recommended standard deviation value (1σ) 

was developed based on the largest reported standard deviation. The recommended standard 

deviation in Table 4-4 is based on the 1975 value, which is calculated to be 18% of the mean. This 

recommendation is favorable to claimants because it results in higher calculated maximum dose rates 

[9]. 

There is no significant trend to the means and maximums plotted in Figure 4-2. As mentioned above, 

effluents from RFP were largely alpha-emitting radionuclides with no substantial gamma component 

with the exception of 241Am. Releases attributable to incidents that might have vented outside 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 17 of 62

buildings, or due to suspension or resuspension of contaminated soil, would not tend to increase the 

gamma exposure rate appreciably due to the relatively large contribution of naturally occurring 

radioactivity to exposure rates measured. Workers subject to environmental doses from such 

incidents would be affected to a far greater extent by internally deposited radionuclides. 

 On-site Environmental Gamma Exposures at Rocky Flats Plant

0

50

100

150

200

250

1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993

Year

mrem/yr

Annual Average Annual Maximum

Figure 4-2. External dose (mrem/yr) at RFP as a function of year. 

Therefore, it is reasonable to assign the average value of 39 ±7 mrem/yr (2,500 hr) to years not 

represented on this table. This value represents the average of means corresponding to the 19 yr for 

which measurements were reported. The assumed standard deviation associated with this average 

value is based on the assumed 18% standard deviation. This dose rate represents the total dose, 

including background, so use of these values in estimating individual worker doses is favorable to the 

claimant.

The listed dose rates in Table 4-4 apply to a best-estimate work year exposure of 2,500 hr, as defined 

in ORAUT-PROC-0060 (ORAUT 2006c).

Ambient onsite gamma is significantly larger (p < 0.05) than ambient gamma measured at “perimeter” 

stations, but only by an average of 9% for years for which data were reported (Dow 1972a, 1973 to 

1976; Rockwell 1977 to 1989; EG&G 1989 to 1993; Kaiser-Hill 1994). This would seem to indicate 

that about 3 mrem/yr (for a 2,500-hr/yr exposure) could be contributed by contamination inside the 

exclusion zone boundary for these years. Thus, increases in airborne contamination will not 

necessarily indicate significant increases in total external dose. However, between 1965 and 1970, 

the large increase in inhalation intake of plutonium is due to soil contamination of the 903 Area before

paving of that area. It is likely that the external dose rate at that location might have been elevated 

compared to other locations at the site due to the 241Am present. Unfortunately, soil concentrations in 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 18 of 62

the barrel storage location are not available, and few soil concentration data are available for the site 

prior to 1969 (Rood and Grogan 1999). In an attempt to estimate external dose to an onsite worker 

from contaminated soils in the vicinity of the 903 storage area, a plutonium soil contamination value of 

26 μCi/m2 (9.6 × 105 Bq/m2

) is assumed, based on the 1973 site environmental report, which reports 

this value as the maximum observed in 1970 just downwind of the 903 Pad. Using Federal Guidance 

Table 4-4. External gamma radiation (mrem/yr).a Blank indicates no data available.

Year

Number of 

measurements

Reported mean

dose rate

Reported 

standard 

deviations (2σ)

Recommended 

standard 

deviation (σ)

Maximum dose 

rateb,c 

1953–1964 39c 7 46

1965–1970 39c 17 56d

1971–1974 39c 7 46

1975 87 32 11 6 38

1976 134 32 10 6 38

1977 98 37 9 7 44

1978 126 37 10 7 44

1979 133 42 3 7 49

1980 131 45 2 8 53

1981 125 38 2 7 45

1982 120 35 1 6 41

1983 135 40 1 7 47

1984 142 42 2 7 49

1985 93 43 2 8 51

1986 147 39 1 7 46

1987 100 44 1 8 52

1988 109 44 2 8 52

1989 132 48 1 9 57

1990 143 44 1 8 52

1991 108 35 1 6 41

1992 176 35 1 6 41

1993 176 39 1 7 46

After 1993 39c 7 46

Mean 1975–1993 39c 7

2 S.D. (2σ) 7

a. Dose rate corresponding to an exposure time of 2,500 hr/yr.

b. Calculated by adding the recommended standard deviation to the mean dose rate, which is 18% of the mean.

c. Average of means reported for 1975 through 1993.

d. Maximum reflects calculated contribution from americium in barrel storage area prior to placement of asphalt pad.

Report (FGR) No. 12 (Eckerman and Ryman 1993) dose conversion factors for surface-contaminated 

soils, assuming that the maximum observed concentration was constant over the entire site, and 

using the mean isotopic ratio reported by Krey et al. (1976) for 241Am/239Pu in RFP soil of 0.13, doses

can be calculated at 1 m above ground surface of approximately 3 mrem/yr (for 2,500-hr/yr exposure). 

Another approach taken to estimate the soil concentration in the barrel storage area before paving 

was based on estimates of the total 239Pu released. According to Weber et al. (1999), the highest 

release estimate for 239Pu in the 903 storage area was on the order of 1,000 g, which corresponds to 

62 Ci. If one assumes that this is spread over the 550- by 475-ft contamination zone of the 903 Area 

originally described (Weber et al. 1999), a maximum estimate of external dose of 17 mrem/yr for 

241Am is obtained [assuming Krey et al. (1976) mean isotopic ratio of 13% for 241Am:239Pu, the 

appropriate FGR 12 dose conversion factor, a depth of contamination of 15 cm, and 2,500-hr/yr

exposure]. 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 19 of 62

Finally, this TBD analysis attempted to ascertain what other sources of external exposure might be 

present. Using dose factors in FGR No. 12 (Eckerman and Ryman 1993), the analysis calculated 

external dose from submersion in air containing 241Am. The 241Am levels were calculated using 

isotopic ratios published by Krey et al. (1976) and modified by RAC when developing soil action levels 

for RFETS. Doses from 241Am in that scenario were negligible, less than 1 μrem/yr. 

The results of these considerations suggest that use of the ambient gamma values for external 

environmental dose is reasonable for unmonitored workers throughout the period from 1953 to the 

present, with the possible exception of the period after plutonium began leaking from the barrel 

storage area and before placement of the asphalt pad in that area. The maximum estimated 

increment to the measured ambient gamma levels was calculated to be 17 mrem/yr for a 2,500-hr/yr 

exposure. Thus, this quantity is added to the measured mean gamma level (39 mrem/yr) applied for 

1965 to 1970, with the resulting value of 56 mrem/yr listed in Table 4-4 as the site-wide maximum. 

4.4 UNCERTAINTY

Uncertainties in estimates of plutonium intake and external dose to an individual employed at RFP are 

associated with natural variations in environmental concentrations, lack of precise information about 

locations and durations of exposures, and limitations of monitoring data. Not all of these uncertainties 

can be quantified.

4.4.1 

4.4.1.1 Intakes Estimated for 1953 to 1964

Uncertainty in Internal Exposure Estimates

The following discussion on uncertainties in the atmospheric dispersion model predictions used to 

estimate intakes for the period from 1953 to 1964 interprets the pertinent text from a Phase II 

document by Rood and Grogan (1999). Uncertainties in model calculations of integrated air 

concentration and intake (Section 4.2.3) arise from model and parameter uncertainty. Model 

uncertainty arises from the inability of the computational algorithms to describe rigorously and 

precisely physical processes that govern the behavior of the system, due either to insufficient 

knowledge of the processes or inability to measure isolated mechanisms driving the processes. 

Model uncertainty is often evaluated in a process called “model validation,” which compares model 

predictions to measured parameters that have not been used to calibrate the model.

Parameter uncertainty arises because of lack of knowledge about, or inability to measure accurately, 

a parameter’s true value. A parameter uncertainty analysis requires the specification of probability 

distributions describing the value of a parameter considered to be uncertain. The assigned 

distribution of a parameter characterizes the degree of belief that the true but unknown value lies 

within a specified range of values. 

The Phase II modeling effort performed parameter uncertainty analysis and model validation. Input 

distributions characterizing the source term, fate and transport calculations, and risk coefficients were 

developed for the model.

The Phase II dispersion modeling for the identified continuous and discrete sources of plutonium to 

the air at RFP used Monte Carlo simulations combined with simple random sampling to propagate 

uncertainty through the model. In simple random sampling, a random value is taken from the 

distribution specified for each uncertain model parameter and a single estimate of the desired 

endpoint is calculated. This process is repeated for a specific number of model realizations. The 

result is an empirical approximation of the probability distribution of the model output.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 20 of 62

In the current application of the Phase II dispersion model, model output (in curies per year of annual 

intake and converted to becquerels per year of intake for Table 4-2) was developed from 500 model 

realizations each year and categorized into a percentile ranking. The ordered statistics for the 5th and 

95th percentiles for 500 model realizations are 25 and 475, respectively. That is, if the output values 

for 500 realizations are sorted in ascending order, the 5th percentile represents the 25th highest value 

and the 95th percentile represents the 475th highest value. The distribution associated with the 

percentiles is not readily described as either normal or lognormal.

The components of uncertainty reflected in the annual intake estimates reflect uncertainty only in the 

source terms and environmental transport. Such components of uncertainty are real in the sense they 

can be derived from measured quantities or inferred from historical records. Uncertainty related to 

exposure scenarios (i.e., location and duration of exposure) were not included in the calculated 

statistics. 

4.4.1.2 Intakes Estimated for 1965 to Present

Uncertainties associated with the reported average annual 239,240Pu air concentrations for the site are 

provided for 1972 to 1976 and 1989 to 1994 in the annual environmental reports (Dow 1972a, 1973 to 

1976; Rockwell 1977 to 1989; EG&G 1989 to 1993; Kaiser-Hill 1994). For these years, error terms 

representing two standard deviations about the mean (at the 95% confidence level) are calculated 

assuming the measurements were normally distributed. In 1977 and 1978, no error terms are 

reported because “they can be misleading and (their use) is considered inappropriate for the data in 

this report” (Rockwell 1978, 1979). These two reports state that the sampling methods would result in 

“nonrandom variations in the measured concentrations,” and the “distribution ... would not be normal.” 

From 1979 to 1988, error terms are reported, but only by sampler location and not normalized to the 

site average. The error terms, when reported, are based on counting error alone, and thus represent 

the minimum error that can be associated with the measurements. Although counting error does 

contribute to data uncertainty, the uncertainty associated with a given average value for the site will 

also be a function of variability in environmental conditions as well as a function of both time and 

location. Thus, the reported confidence limits (CLs) are not useful in estimating uncertainty 

associated with a site average because they would undoubtedly underestimate that uncertainty.

4.4.2 

Unquantifiable uncertainty in external exposures results from the lack of readily available data before

1975 or after 1993. However, onsite measurements made during that 19-yr period indicate no 

significant upward trend to indicate that Plant operations are increasing background. Published data 

for environmental external measurements have normal statistics associated with them. The data 

published in Table 4-4 vary considerably in the expression of uncertainty presented in the annual 

environmental reports. For years before 1977, no uncertainty data are available. For other years, the 

uncertainty varies from as much as 18% (1σ) for 1975 to less than 2% for 1983. This TBD

recommends using the maximum uncertainty available in the literature, 18%, which is represented by 

1981 data. The annual recommended values of uncertainty, expressed in terms of 1σ, are listed in 

the fifth column of Table 4-4. 

Uncertainties in External Dose Estimate

4.5 ATTRIBUTIONS AND ANNOTATIONS

Where appropriate in this TBD, bracketed callouts have been inserted to indicate information, 

conclusions, and recommendations provided to assist in the process of worker dose reconstruction. 

These callouts are listed here in the Attributions and Annotations section with information provided to 

identify the source and justification for each associated item. Conventional references are provided in 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 21 of 62

the next section, linking data, quotations, and other information to documents available for review on 

the NIOSH Project computer network. 

[1] McDowell-Boyer, Laura M. Oak Ridge Associated Universities (ORAU) Team. Environmental 

Engineer. July 2006.

The recommendation to ignore contributions of 238Pu and 241Pu is based on the facts that 

(1) their total alpha activity contributions are less than 5% of those of 239Pu and 240Pu, based 

on the reported isotopic composition of plutonium at RFP, and (2) the maximum inhalation 

organ dose factors for 238Pu and 241Pu are equal to or less than those for 239Pu and 240Pu. 

Thus, 238Pu and 241Pu will not contribute more than a few percent of the dose from plutonium.

[2] ORAUT-PROC-0031, DOE Technical Basis Document Development, Review, and Approval 

Process (ORAUT 2006d).

This procedure provides guidance in TBD preparation, and specifies that maximum site-wide 

annual median intakes via inhalation will be provided.

[3] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

The measurements by Poet and Martell (1972) indicated that the mean activity ratio in soil 

ranged from 0.03 to 0.17, but the authors acknowledged that low recovery yields associated 

with their laboratory procedures resulted in large errors for their 241Am results. Krey et al. 

(1976) measured the 241Am/239Pu ratios in soil, and found a range from 0.10 to 0.20, with a 

mean of 0.13, and standard deviation of 0.03. Both authors acknowledged that the ratio would 

increase over time and peak 70 to 80 yr after plutonium purification (around 2030). Assuming 

the initial isotopic composition of plutonium from Section 4.2.1, with 241Pu at 0.36%, the 

resulting peak ratio would be about 0.18 (Poet and Martell claimed this peak was 0.54, but had 

assumed an isotopic ratio of 1% for 241Pu, which is almost 3 times too high). In 1996, Litaor 

and Allen (1996) found an average onsite ratio of 0.19, although indicated difficulties related to 

high analytical errors with 241Am. Therefore, due to uncertainty in the relative movement of the 

two isotopes in soil, a higher value of 0.30 is recommended.

[4] Rood, Arthur S. K-Spar Inc. Scientific Consulting. President. July 2006.

The puff trajectory model, RATCHET (Regional Atmospheric Transport Code for Hanford 

Environmental Tracking), was adapted by Mr. Rood from its use for the Phase II Historical 

Public Exposures Studies for RFP for use in estimating onsite inhalation intakes from 1953 to 

1964. The model and adaptations are described in Attachment A, Section A.2.

[5] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Due to variations in the original source of particles (fires, cutting oil, etc.) and environmental 

factors, it is recommended that the dose reconstructor always make a selection of dose factor 

that is favorable to claimants with regard to plutonium solubility.

[6] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. January 2007. 

The recommendation to assume the default ICRP Publication 66 AMAD of 1.0 μm, 

“recommended for exposure in the general environment” during certain periods results in using 

inhalation organ dose factors that are higher than those for larger respirable particles (those 

on the order of 5 μm). The cited literature indicates that intakes from plutonium released 

routinely or from fires during the 1953-to-1966 and 1970-to-1993 periods are possibly smaller 

than the 5- μm ICRP Publication 66 default recommended for “occupational exposure settings” 

due in part to the presence of HEPA filter banks at the emission points.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 22 of 62

[7] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Plutonium-contaminated particles suspended or resuspended from soil and other surfaces are 

known to contribute a significant portion of the airborne activity of plutonium in certain areas of 

the RFP site, and many of these particles are better characterized by an AMAD of 5 μm. From 

1967 to 1969, a number of high-wind events occurred during and after removal of leaking 

barrels containing plutonium-contaminated cutting oil in the 903 Area, which resulted in 

dispersal of significant quantities of contaminated soil particulates, mainly in the easterly to 

southeasterly direction from the 903 Area. The site-wide maximum air concentrations and, 

thus, estimated intakes are associated with this region of RFP. The airborne plutonium in this 

region is best characterized by an AMAD of 5 μm. After 1993, production had ceased, and 

thus it is reasonable to expect that the main source of airborne plutonium would be 

resuspension from soil or surfaces, and HEPA-mediated emissions would no longer have 

occurred.

[8] ORAUT-PROC-0031, DOE Technical Basis Document Development, Review, and Approval 

Process (ORAUT 2006d).

This procedure provides guidance in TBD preparation and specifies that a site average value 

be provided along with the standard deviation and a maximum onsite dose rate (derived by 

adding the standard deviation to the average).

[9] Little, Craig A. ORAU Team. Radioecologist/Health Physicist. 2006

The average of the reported standard deviations (2σ) without the 1975-to-1978 values is 

approximately 5. The recommended value of 1σ is approximately 10 times higher than most 

reported values due to the uncertainty posed by the unexplained larger variabilities seen in 

1975, 1976, and 1978. This is an upper bound on the uncertainty and, thus, the resulting 

estimates of the maximum dose rate are favorable to claimants. 

[10] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Rope et al. (1999, pp. III-43 and III-44) did an extensive review of environmental data available 

for the RFP site and based this least-squares, best-fit estimate of the plutonium contribution to 

TLLα on data collected by the Health and Safety Laboratory and Dow, making standard 

temperature and pressure corrections as necessary. The results were very close to an 

estimate made by another researcher, who did not do a best-fit analysis, but rather assumed a 

value between 33% and 50% based on a log-log plot of data collected by the Colorado 

Department of Health. The Rope et al. value appears to carry more scientific weight, yet is not 

in conflict with the other results. Therefore, the value of 0.36 is considered the best estimate 

available for the period of interest.

[11] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

An electronic presentation addressing special monitoring during decommissioning and 

demolition projects at RFETS (www.rfets.gov/eddie/Download/Main.asp?RID=163) indicates 

that impacts from various demolition projects undertaken in 1999 (Building 779 glovebox stripout, Building 729 stack removal, Building 788 demolition, Building 729 demolition, Building 729 

clarifier tank removal) were not significant in terms of measured isotopic air concentrations.

[12] Rood, Arthur S. K-Spar Inc. Scientific Consulting. President. July 2006.

Mr. Rood developed the RATCHET application for the Phase II Historical Public Exposure 

Studies project, and made modifications to the model for this study, utilizing the same source 

terms identified in the earlier work.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 23 of 62

[13] Rood, Arthur S. K-Spar Inc. Scientific Consulting. President. July 2006.

The Building 776 stack conforms to the U. S. Environmental Protection Agency (EPA) 

definition of good engineering practice (GEP) design. According to the EPA 1995 Building 

Profile Input Program, building wake effects extend out to 5 times the lesser of the building 

height or the building perimeter width, such that Building 771 is the only building within the 

sphere of influence of the 776 stack. The 776 stack must be at least 29 m high (since the 

Building 771 height is 11.6 m) to conform to GEP and, thus, to be free of the effects of building 

wakes. Since the 776 stack is 44 m high, building wake effects are not a concern. 

[14] Rood, Arthur S. K-Spar Inc. Scientific Consulting. President. July 2006.

The other elevated sources modeled were the Building 776 roof vents. Because some of the 

roof vents were an inverted “J” type, effluent was directed down toward the roof, thereby 

distributing the source across the roof surface. To account for this, Building 776 was modeled 

not as a point source but as an elevated area source, and initial dispersion coefficients were 

assigned. The coefficients implicitly account for the effects of building wakes by driving the 

plume initially down to the ground surface.

[15] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

See Attribution note [10].

[16] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

There is no evidence that background radioactivity in the Denver area would be significantly 

different from that in the RFP area; therefore, this assumption is reasonable.

[17] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

Radionuclides other than 239/241Pu and 241Am that have been released from RFP and contribute 

less than 1-mrem/yr dose to any organ in the year of maximum release are not expected to 

contribute more than 5% of the total environmental dose when compared to the maximum 

dose contributions of 239/240Pu and 241Am in the same year. This was verified by comparing the 

maximum estimated doses for these other radionuclides (Attachment B, Tables B-1 to B-3) 

and the site-wide maximum doses associated with the 239/240Pu and 241Am inhalation intake 

values in Tables 4-2 and 4-3.

[18] McDowell-Boyer, Laura M. ORAU Team. Environmental Engineer. July 2006.

This statement is supported by the text following it, which demonstrates considerable effort by 

ChemRisk to review effluent monitoring data, including raw data when necessary. It is 

important to recognize that ChemRisk reevaluated the uncertainty associated with the data 

reviewed, and proposed larger uncertainties due to possible measurement and recording 

errors.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 24 of 62

REFERENCES

CDPHE (Colorado Department of Public Health and Environment), 2000, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, First 

Quarter 2000, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2001a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, First 

Quarter 2001, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2001b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site,

Second Quarter 2001, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2001c, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, Third 

Quarter 2001, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2002a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, First 

Quarter 2002, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2002b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site,

Second Quarter 2002, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2002c, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, Third 

Quarter 2002, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment) 2003a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, First 

Quarter 2003, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2003b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site,

Second Quarter 2003, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2003c, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, Third 

Quarter 2003, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2003d, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, Fourth 

Quarter 2003, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2004a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, First 

Quarter 2004, Denver, Colorado. 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 25 of 62

CDPHE (Colorado Department of Public Health and Environment), 2004b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, Third 

Quarter 2004, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2005a, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, First 

Quarter 2005, Denver, Colorado. 

CDPHE (Colorado Department of Public Health and Environment), 2005b, Environmental Surveillance 

Report on the U.S. Department of Energy Rocky Flats Environmental Technology Site, Third 

Quarter 2005, Denver, Colorado.

ChemRisk (ChemRisk, a division of McLaren/Hart), 1992, Reconstruction of Historical Rocky Flats 

Operations & Identification of Release Points, Project Tasks 3 and 4 for Phase I, prepared for 

the Colorado Department of Public Health and Environment, Alameda, California, August.

ChemRisk (ChemRisk, a division of McLaren/Hart), 1994a, Estimating Historical Emissions from 

Rocky Flats 1952–1989, Project Task 5 for Phase I, prepared for the Colorado Department of 

Public Health and Environment, Alameda, California, March.

ChemRisk (ChemRisk, a division of McLaren/Hart), 1994b, Dose Assessment for Historical 

Contaminant Releases from Rocky Flats, Project Task 8 for Phase I, prepared for the 

Colorado Department of Public Health and Environment, Alameda, California, September.

DOE (U.S. Department of Energy), 1980, Final Environmental Impact Statement, Rocky Flats Plant 

Site, DOE/EIS-064, Golden, Colorado. 

Dow (Dow Chemical U.S.A.), 1972a, Annual Report: Environmental Safeguard ’71, January – 

December 1971, RFP-ENV-718, Rocky Flats Division, Golden, Colorado.

Dow (Dow Chemical U.S.A.), 1972b, Rocky Flats Monthly Monitoring Results, January – December 

1972, Rocky Flats Division, Golden, Colorado.

Dow (Dow Chemical U.S.A.), 1973, Annual Environmental Monitoring Report, Rocky Flats Plant, 

January – December 1972, RFP-ENV-72, Rocky Flats Division, Golden, Colorado.

Dow (Dow Chemical U.S.A.), 1974, Annual Environmental Monitoring Report, Rocky Flats Plant, 

January - December 1973, RFP-ENV-73, Rocky Flats Division, Golden, Colorado.

Dow (Dow Chemical U.S.A.), 1975, Annual Environmental Monitoring Report, Rocky Flats Plant, 

January – December 1974, RFP-ENV-74, Rocky Flats Division, Golden, Colorado.

Dow (Dow Chemical U.S.A.), 1976, Annual Environmental Monitoring Report, Rocky Flats Plant, 

January – December 1975, RFP-ENV-75, Rocky Flats Division, Golden, Colorado.

Eckerman, K. F., and J. C. Ryman, 1993, External Exposure to Radionuclides in Air, Water, and Soil,

Federal Guidance Report No. 12, EPA-402-R-93-081, U.S. Environmental Protection Agency, 

Washington, D.C.

EG&G (EG&G Rocky Flats), 1989, Rocky Flats Plant Site Environmental Report for 1989, January 

through December 1989, RFP-ENV-89, Rocky Flats Plant, Golden, Colorado.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 26 of 62

EG&G (EG&G Rocky Flats), 1990, Rocky Flats Plant Site Environmental Report for 1990, January 

through December 1990, RFP-ENV-90, Rocky Flats Plant, Golden, Colorado.

EG&G (EG&G Rocky Flats), 1991, Rocky Flats Plant Site Environmental Report for 1991, January 

through December 1991, RFP-ENV-91, Rocky Flats Plant, Golden, Colorado.

EG&G (EG&G Rocky Flats), 1992, Rocky Flats Plant Site Environmental Report for 1992, January 

through December 1992, RFP-ENV-92, Rocky Flats Plant, Golden, Colorado.

EG&G (EG&G Rocky Flats), 1993, Site Environmental Report for 1993, January through December 

1993, RFP-ENV-93, Rocky Flats Environmental Technology Site, Golden, Colorado.

EG&G (EG&G Rocky Flats), 1995. Reference to be completed. 

Grogan, H. A., W. K. Sinclair, and P. G. Voillequé, 2000, Assessing Risks of Exposure to Plutonium, 

Final Report, RAC Report No. 5-CDPHE-RFP-1998-FINAL (Rev. 2), Risk Assessment 

Corporation, Neeses, South Carolina, February.

Hayden, J.A. 1976. “Characterization of Environmental Plutonium by Nuclear Track Techniques.” In 

Atmosphere-Surface Exchange of Particulate and Gaseous Pollutants (1974). ERDA 

symposium series 38, CONF-740921. National Technical Information Service, Springfield, 

Virginia. 648–670.

ICRP (International Commission on Radiological Protection), 1975, Report of the Task Group on 

Reference Man, Publication 23, Pergamon Press, Oxford, England. 

ICRP International Commission on Radiological Protection), 2001, ICRP CD1: Database of Dose 

Coefficients: Worker and Members of the Public, Pergamon Press, Oxford, England. 

Kaiser-Hill (Kaiser-Hill Company, LLC), 1994, Site Environmental Report for 1994, RFP-ENV-94, 

Rocky Flats Environmental Technology Site, Golden, Colorado.

Krey, P., E. Hardy, H. Volchok, L. Toonkel, R. Knuth, and M. Coppes, 1976, Plutonium and Americium 

Contamination in Rocky Flats Soil–1973, Report HASL-304, U.S. Atomic Energy Commission, 

Health and Safety Laboratory, New York, New York.

Litaor, M. I., and L. Allen, 1996, “A Comprehensive Appraisal of 241Am in Soils Around Rocky Flats, 

Colorado,” Health Physics, volume 71, number 3, pp. 347–357.

Mann, J.R. and R.A. Kirchner. 1967. “Evaluation of Lung Burden Following Acute Inhalation Exposure 

to Highly Insoluble PuO2.” Health Phys. 13: 877–882.

O’Kula, K. R., and C. E. Murphy, Jr., 2001, Crediting Tritium Deposition in Accident Analysis, WSRCMS-2001-00112, Westinghouse Savannah River Company, Aiken, South Carolina.

ORAUT (Oak Ridge Associate Universities Team), 2006a, Rocky Flats Plant – Site Description, 

ORAUT-TKBS-0011-2, Rev. 01, Oak Ridge, Tennessee.

ORAUT (Oak Ridge Associated Universities Team), 2006b, Rocky Flats Plant – Occupational 

External Dose, ORAUT-TKBS-0011-6, Rev. 01, Oak Ridge, Tennessee.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 27 of 62

ORAUT (Oak Ridge Associated Universities Team), 2006c, Occupational Onsite Ambient Dose 

Reconstruction for DOE Sites, ORAUT-PROC-0060, Rev. 00, Oak Ridge, Tennessee, June 

28.

ORAUT (Oak Ridge Associated Universities Team), 2006d, Technical Basis Document Development, 

Review, and Approval Process, ORAUT-PROC-0031, Rev. 01 PC-1, Oak Ridge, Tennessee, 

February 10.

Poet, S. E., and E. A. Martell, 1972, “Plutonium-239 and Americium-241 Contamination in the Denver 

Area,” Health Physics, volume 23, pp. 537–546.

Putzier, E. A., 1982, The Past 30 Years at Rocky Flats Plant, Rockwell International Energy Systems 

Group, Rocky Flats Plant, Golden, Colorado, November.

RFETS (Rocky Flats Environmental Technology Site), 1996a, Quarterly Environmental Monitoring 

Report, January – March 1996, RF/ER-96-0023.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1996b, Quarterly Environmental Monitoring 

Report, April – June 1996, RF/ER-96-0045.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1996c, Quarterly Environmental Monitoring 

Report, July – September 1996, RF/RMRS-96-0063, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1996d, Quarterly Environmental Monitoring 

Report, October – December 1996, RF/RMRS-97-005, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1997a, Quarterly Environmental Monitoring 

Report, January - March 1997, RF/RMRS-97-027, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1997b, Quarterly Environmental Monitoring 

Report, April - June 1997, RF/RMRS-97-050, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1997c. Quarterly Environmental Monitoring 

Report, July - September 1997, RF/RMRS-97-114.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1997d, Quarterly Environmental Monitoring 

Report, October - December 1997, RF/RMRS-98-216.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1998a, Quarterly Environmental Monitoring 

Report, January - March 1998, RF/RMRS-98243.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1998b, Quarterly Environmental Monitoring 

Report, April - June 1998, RF/RMRS-98243.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1998c, Quarterly Environmental Monitoring 

Report, July - September 1998, RF/RMRS-98287.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1998d, Quarterly Environmental Monitoring 

Report, October - December 1998, RF/RMRS-98287.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1999a, Quarterly Environmental Monitoring 

Report, October - December 1998, RF/RMRS-99-329.UN, Golden, Colorado.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 28 of 62

RFETS (Rocky Flats Environmental Technology Site), 1999b, Quarterly Environmental Monitoring 

Report, January - March 1999, RF/RMRS-99-375.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1999c, Quarterly Environmental Monitoring 

Report, April - June 1999, RF/RMRS-99-421.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 1999d, Quarterly Environmental Monitoring 

Report, July - September 1999, RF/RMRS-99-465.UN, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2000a, Quarterly Environmental Monitoring 

Report, January - March 2000, U.S. Department of Energy, Rocky Flats Field Office, Golden, 

Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2000b, Quarterly Environmental Monitoring 

Report, April - June 2000, U.S. Department of Energy, Rocky Flats Field Office, Golden, 

Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2000c, Quarterly Environmental Monitoring 

Report, July - September 2000, U.S. Department of Energy, Rocky Flats Field Office, Golden, 

Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2001a, Quarterly Environmental Monitoring 

Report, October - December 2000, U.S. Department of Energy, Rocky Flats Field Office, 

Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2001b, Quarterly Environmental Monitoring 

Report, January - March 2001, U.S. Department of Energy, Rocky Flats Field Office, Golden, 

Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2001c, Quarterly Environmental Monitoring 

Report, April - June 2001, U.S. Department of Energy, Rocky Flats Field Office, Golden, 

Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2002a, Quarterly Environmental Monitoring 

Report, October - December 2001, U.S. Department of Energy, Rocky Flats Field Office, 

Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2002b. Quarterly Environmental Monitoring 

Report, January - March 2002, Rocky Flats Environmental Technology Site, US Department of 

Energy, Rocky Flats Field Office, Golden, Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2002c, Quarterly Environmental Monitoring 

Report, July - September 2002, U.S. Department of Energy, Rocky Flats Field Office, Golden, 

Colorado.

RFETS (Rocky Flats Environmental Technology Site), 2003a, Quarterly Environmental Monitoring 

Report, October - December 2002, U.S. Department of Energy, Rocky Flats Field Office, 

Golden, Colorado.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 29 of 62

RFETS (Rocky Flats Environmental Technology Site), 2003b, Quarterly Environmental Monitoring 

Report, January - March 2003, U.S. Department of Energy, Rocky Flats Field Office, Golden, 

Colorado.

RMRS (Rocky Mountain Remediation Services, L.L.C.), 1995a, Monthly Environmental Monitoring 

Report , August 1995, RF/ER-95-0106-UN, Rocky Flats Environmental Technology Site, 

Golden, Colorado. 

RMRS (Rocky Mountain Remediation Services, L.L.C.), 1995b, Monthly Environmental Monitoring 

Report, October 1995, RF/ER-95-0107-UN, Rocky Flats Environmental Technology Site, 

Golden, Colorado. 

Rockwell (Rockwell International), 1977, Annual Environmental Monitoring Report, January – 

December 1976, RFP-ENV-76, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1978, Annual Environmental Monitoring Report, January – 

December 1977, RFP-ENV-77, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1979, Annual Environmental Monitoring Report, January – 

December 1978, RFP-ENV-78, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1980, Annual Environmental Monitoring Report, January – 

December 1979, RFP-ENV-79, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1981, Annual Environmental Monitoring Report, January – 

December 1980, RFP-ENV-80, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1982, Annual Environmental Monitoring Report, January – 

December 1981, RFP-ENV-81, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1983, Annual Environmental Monitoring Report, January – 

December 1982, RFP-ENV-82, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1984, Annual Environmental Monitoring Report, January – 

December 1983, RFP-ENV-83, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1985, Annual Environmental Monitoring Report, January – 

December 1984, RFP-ENV-84, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1986, Annual Environmental Monitoring Report, January – 

December 1985, RFP-ENV-85, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1987, Annual Environmental Monitoring Report, January – 

December 1986, RFP-ENV-86, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1988, Annual Environmental Monitoring Report, January – 

December 1987, RFP-ENV-87, Rocky Flats Plant, Golden, Colorado.

Rockwell (Rockwell International), 1989, Rocky Flats Plant Site Environmental Report for 1988, 

January through December 1988, RFP-ENV-88, Rocky Flats Plant, Golden, Colorado.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 30 of 62

Rood, A. S., 1999, Estimated Exposure and Lifetime Cancer Incidence Risk from Routine Plutonium 

Releases at the Rocky Flats Plant, Final Report, RAC Report No. 8-CDPHE-RFP-1997-FINAL, 

Radiological Assessment Corporation, Neeses, South Carolina, August.

Rood, A. S., and H. A. Grogan, 1999, Comprehensive Assessment of Exposure and Lifetime Cancer 

Incidence Risk from Plutonium Released from the Rocky Flats Plant, 1953-1989, RAC Report 

13-CDPHE-RFP-1999-Final, Radiological Assessments Corporation, Neeses, South Carolina, 

September.

Rope, S. K, K. R. Meyer, M. J. Case, H. A. Grogan, D. W. Schmidt, M. Dreicer, and T. F. Winsor, 

1999, Evaluation of Environmental Data for Historical Public Exposures Studies on Rocky 

Flats, Task 4: Evaluation of Environmental Data, Final Report, Revision 1, RAC Report 1-

CDPHE-RFP-1997-Final (Rev. 1), Radiological Assessments Corporation, Neeses, South 

Carolina, August.

Voillequé, P. G., 1999a, Estimated Airborne Releases of Plutonium During the 1957 Fire in Building 

71, RAC Report 10-CDPHE-RFP-1999-FINAL, Radiological Assessments Corporation,

Neeses, South Carolina, August.

Voillequé, P. G., 1999b, Estimated Airborne Releases of Plutonium During the 1969 Fire in Buildings 

776/777, RAC Report 9-CDPHE-RFP-1999-FINAL, Radiological Assessments Corporation,

Neeses, South Carolina, August.

Voillequé, P. G., 1999c, Review of Routine Releases of Plutonium in Airborne Effluents at Rocky 

Flats, RAC Report 6-CDPHE-RFP-1997-FINAL, Radiological Assessments Corporation,

Neeses, South Carolina, August.

Voillequé, P. G., 1999d, Results of Screening Calculations to Assess the Relative Importance of 

Rocky Flats Uranium Releases, RAC Report No. 11-CDPHE-RFP-1999-FINAL, Radiological 

Assessments Corporation, Neeses, South Carolina. August.

Weber, J. M., A. S. Rood, H. R. Meyer, and J. E. Till, 1999, Development of the Rocky Flats Plant 903 

Area Plutonium Source Term, RAC Report 8-CDPHE-RFP-1998-FINAL (Rev. 1), Radiological 

Assessments Corporation, Neeses, South Carolina, August.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 31 of 62

GLOSSARY

alpha emitters

Unstable isotopes which decay by emitting alpha particles. See alpha particle. 

alpha particle

Positively charged particles of discrete energies emitted by certain radioactive materials; alpha 

particles usually expend their energy in short distances and will not usually penetrate the outer 

layer of skin; they are a significant hazard only when taken into the body where their energy is 

absorbed by tissues.

becquerel

A special unit of radioactivity. One becquerel equals 1 disintegration per second.

beta radiation

Radiation consisting of charged particles of very small mass (i.e., the electron) emitted 

spontaneously from the nuclei of certain radioactive elements. Most (if not all) of the direct 

fission products emit beta radiation. Physically, the beta particle is identical to an electron 

moving at high velocity.

curie

A special unit of radioactivity. One curie equals 3.7 × 1010 nuclear transitions per second.

depleted uranium

Uranium that is a byproduct of uranium enrichment, containing a lower than natural isotopic 

abundance of 235U.

dosimeter

A device used to measure the quantity of radiation received. A holder with radiation-absorbing 

elements (filters) and an insert with radiation-sensitive elements packaged to provide a record 

of absorbed dose or dose equivalent received by an individual. See thermoluminescent 

dosimeter. 

dosimetry

The science of assessing absorbed dose, dose equivalent, effective dose equivalent, etc., 

from external or internal sources of radiation. 

enriched uranium

Uranium enhanced from its natural state to contain a higher percentage of the isotope 235U. 

exposure

As used in the technical sense, exposure refers to a measure expressed in roentgens (R) of 

the ionization produced by photons (i.e., gamma and X-rays) in air. 

film

In general, a "film packet" that contains one or more pieces of film in a light-tight wrapping. 

When developed, the film has an image caused by radiation that can be measured using an 

optical densitometer.

film dosimeter

A small packet of film within a holder that attaches to a wearer.
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 32 of 62

gamma rays

Electromagnetic radiation (photons) originating in atomic nuclei and accompanying many 

nuclear reactions (e.g., fission, radioactive decay, and neutron capture). Physically, gamma 

rays are identical to X-rays of high energy, the only essential difference being that X-rays do 

not originate in the nucleus. 

isotope

Elements having the same atomic number but different atomic weights; identical chemically 

but having different physical and nuclear properties. 

operating area

Designation of major onsite operational work areas.

radiation

Alpha, beta, neutron, and photon radiation. 

radioactivity

The spontaneous emission of radiation, generally alpha or beta particles, gamma rays, and 

neutrons from unstable nuclei.

radionuclide

A radioactive isotope of an element, distinguished by atomic number, atomic weight, and 

energy state. 

rem

A unit of dose equivalent equal to the product of the number of rad absorbed and the quality 

factor.

thermoluminescent dosimeter (TLD)

A holder containing solid chips of material that when heated will release stored energy as light. 

The measurement of this light provides a measurement of absorbed dose. 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 33 of 62

TABLE OF CONTENTS 

SECTION TITLE

A.1 Introduction ...........................................................................................................................

PAGE

34

A.2 Measurement of Total Long-Lived Alpha Activity and Plutonium in Air ................................... 34

A.3 Atmospheric Transport Modeling............................................................................................ 36

LIST OF TABLES

TABLE TITLE

A-1 Monthly average concentrations of total long-lived alpha activity in onsite 

air samples, October 1964 to December 1971 .......................................................................

PAGE

47

A-2 Estimated annual average concentrations of 239,240Pu in onsite air samples 

between 1965 and 1994 based on measurement data provided in Table 

A-1, RFP annual environmental reports, RFETS monthly and quarterly 

monitoring reports, and CDPHE quarterly environmental surveillance 

reports....................................................................................................................................50

A-3 Annual average concentrations of plutonium in air for three location 

groups, RFP contractor monitoring, 1971 to 1990)................................................................. 51

A-4 Data from Table III-4 in Rope et al. (1999) showing a comparison of 

239,240Pu concentrations in onsite and offsite air, measured by CDPHE .................................. 52

A-5 Data from Table B-14 in Rope et al. (1999) showing annual average 

concentrations of 239,240Pu in Denver air, 1971 to 1989........................................................... 53

A-6 Corrected annual average concentrations of 239,240Pu in air at perimeter 

monitoring stations.................................................................................................................54

LIST OF FIGURES

FIGURE TITLE

A-1 Location of samplers operated by RFP contractor..................................................................

PAGE

40

A-2 Location of onsite computational nodes used to predict average onsite air 

concentrations for RFP industrial area ................................................................................... 41

A-3 Annual average 239,240Pu concentrations in air as a function of time for 

particles < 30-μm AED in RFP industrial area ........................................................................ 42

A-4 Annual average 239,240Pu concentrations in air as a function of time for 

particles < 30-μm AED in the perimeter area surrounding RFP.............................................. 43

A-5 Locations of computational nodes used to compute annual average 

perimeter concentrations shown in Figure A-6 ....................................................................... 44

A-6 Eastern part of RFP industrial area, showing locations of CDPHE air 

monitoring stations D-1 to D-5 ................................................................................................ 45

A-7 Locations of offsite air samplers in 1975 ................................................................................ 46

ATTACHMENT A

ESTIMATION OF PLUTONIUM AIR CONCENTRATIONS AT THE ROCKY FLATS PLANT

Page 1 of 22
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 34 of 62

A.1 INTRODUCTION 

Occupational environmental dose reconstruction for RFP requires that 239,240Pu air concentrations be 

estimated for onsite locations as a function of time. Actual measurements of 239,240Pu in air for the 

RFP onsite environment are generally preferable to modeled concentrations because modeling relies 

on measurements of parameters related to source terms and meteorology that are often spatially and 

temporally averaged, thus adding considerable uncertainty to estimates for particular locations or 

points in time. Further, models often cannot address all the processes or source terms that affect the 

air concentration. However, there are periods in the RFP operational history when useful 

measurements of 239,240Pu in air are not available. This attachment describes the availability of 

monitoring data and modeled estimates and addresses the suitability of each type of estimate for use 

in occupational dose reconstruction for particular periods. In addition, it provides the technical basis 

of atmospheric transport calculations supporting the estimated 239,240Pu intakes. 

A.2 MEASUREMENT OF TOTAL LONG-LIVED ALPHA ACTIVITY AND PLUTONIUM IN AIR

Task 4 of the Phase II Historical Public Exposures Studies on RFP (Rope et al. 1999) contains an indepth historical review and compilation of air monitoring data. This attachment relies on conclusions

from that review to determine the usefulness of onsite air monitoring data in estimating 239,240Pu intake 

from environmental (outdoor) exposures. 

According to Rope et al. (1999), 239,240Pu concentrations in air were not measured at RFP until 1969, 

when the Colorado Department of Health (now called the Colorado Department of Public Health and 

Environment) began reporting onsite air concentrations. Between the start of operations in 1952 and 

1969, gross alpha activity in air was measured by the RFP contractor, but earlier data during this 

period (up to 1964) were considered by Rope et al. (1999, pp. III-33–III-34) to be of limited value for 

assessing concentrations of long-lived alpha emitters such as 239,240Pu. Prior to 1960, measurements 

were not made in a way that enabled estimation of the long-lived alpha component of the gross alpha 

measurements. Thus, there is no reliable way to estimate 239,240Pu in air before 1960 from air 

monitoring data. From 1960 to 1964, counts of gross alpha activity were made near the time of 

collection (4 hr after) and 1 wk later, such that TLLα activity concentrations could be estimated. 

Estimates of 239,240Pu concentrations can be made from TLLα activity concentrations in a manner 

described later in this attachment. However, data collected between 1960 and 1964 were of limited 

value to the Task 4 studies because they were reported as one onsite number, with the maximum and 

minimum individual count values shown. Results from individual samplers could not be obtained. 

Thus, data before 1964 were not suitable or readily available for this TBD. Due to these inadequacies 

in monitoring data during the period between 1952 and 1964, this TBD relied on atmospheric 

dispersion modeling conducted for the Phase II study for developing estimates of 239,240Pu 

concentrations in onsite air. This section describes the Phase II model and application for the present 

purposes.

From October 1964 until December 1971, the RFP contractor reported daily TLLα activity 

concentrations in air for individual onsite samplers (Rope et al. 1999, p. III-34). The samplers 

included S-1 through S-10, S-50, and S-51. The locations of the onsite samplers during this period 

are shown in the upper “1974” drawing in Figure A-1 (reproduced from Figure B-6 in Rope et al. 

1999). Monthly average concentrations derived from these measurements, in fCi/m3

 (1 × 10-15 Ci/m3), 

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are reproduced from Table B-6 in Rope et al. in Table A-1. (Note: Figures and tables appear at the 

end of this attachment.)

In 1969, the Colorado Department of Health began monitoring 239,240Pu in air at the RFP (Rope et al. 

1999, p. III-21) near the east security fence. Rope et al. (1999, p. III-23) used data from the CDPHE 

air monitoring stations to evaluate the predicted impact of contaminated soil after placement of the 

asphalt pad in the 903 Area. These measurements complement the air monitoring conducted by the 

RFP contractor and the Health and Safety Laboratory, which began monitoring air in the same vicinity 

(on the east security fence downwind of the 903 Area) in 1970 (Rope et al. 1999, p. III-12).

In 1970, the RFP environmental monitoring program began to include routine monitoring of 239,240Pu in 

air (Rope et al. 1999, p III-63). However, results for 239,240Pu, rather than TLLα, were not reported in 

RFP annual environmental reports until 1973 (Dow 1972a, 1973 to 1976; Rockwell 1977 to 1989; 

EG&G 1989 to 1993; Kaiser-Hill 1994). Table A-2 lists annual air concentrations, averaged over the 

onsite samplers and compiled from annual environmental reports through 1994 and the monthly data 

in Table A-1, along with the maximum onsite monthly measurement corresponding to that year. The 

units have been converted to femtocuries per cubic meter for consistency with Table A-1. Sampling 

locations are specified, and can be visualized from Figure A-1. The samplers were renumbered in 

1975, as indicated in this figure. The annual average was not provided in the annual reports for 1977 

to 1988, but was calculated from the monthly volume-weighted averages for each sampling location. 

Beginning in 1977, measurements were not reported for all samplers, but for sampling stations with 

the greatest potential for elevated airborne radioactivity. Thus, results after 1976 are not as 

representative of an average for the RFP industrial area, but for the onsite areas likely to be highest in 

concentrations of 239,240Pu in air.

To estimate the 239,240Pu air concentration based on TLLα activity concentration for data from 1965 to 

1973 in Table A-2, a conversion factor was adopted from the review of available information on this 

topic provided in Rope et al. (1999, beginning on p. III-42). Rope et al. evaluated data collected in the 

early 1970s and derived a least-squares best fit to the data result of 36% plutonium contribution to the 

TLLα. Some of the TLLα activity in onsite air is due to naturally occurring alpha emitters and fallout 

plutonium. The remainder can be attributed to plutonium, americium, and uranium from RFP (Rope et 

al. 1999). A conversion factor of 0.36 was assumed for converting TLLα activity concentrations from 

the annual environmental reports to 239,240Pu activity concentrations [10].

The annual environmental reports (Dow 1972a, 1973 to 1976; Rockwell 1977 to 1989; EG&G 1989 to 

1993; Kaiser-Hill 1994) provide 95% CLs for the average annual 239,240Pu air concentration for RFP for 

1972 to 1976 and 1989 to 1994. For these years, the standard deviation was reported as the 95% 

CLs, assuming the measurements were normally distributed. In 1977 and 1978, no standard 

deviations were reported because “they can be misleading and (their use) is considered inappropriate 

for the data in this report” (Rockwell 1978, 1979). These two reports state that the sampling methods 

would result in “nonrandom variations in the measured concentrations,” and the “distribution ... would 

not be normal.” Standard deviations are reported for 1979 to 1988, but only by sampler location, and 

not normalized to the site average. The CLs, when reported, are based on counting error alone, and 

thus represent the minimum error that can be associated with the measurements. Although counting 

error does contribute to uncertainty in the data, the uncertainty associated with a given average value 

for the site will also be a function of variability in environmental conditions as a function of time and 

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location. Thus, the reported CLs are not useful for estimating uncertainty associated with a site 

average because they would undoubtedly underestimate that uncertainty.

Annual environmental reports were discontinued after 1994 as a result of the change in the RFP 

mission, so site-wide measurements of 239,240Pu in air after 1994 are not as readily accessible. 

Between 1995 and July 1998, onsite ambient air concentrations of 239,240Pu are reported in RFETS 

EG&G and other Monthly and Quarterly Monitoring Reports (RMRS 1995a,b; RFETS 1996a to 

1998d). In 1995, an onsite average air concentration can be calculated from the reported data for 

approximately 20 sampling locations, and a site-wide maximum annual average corresponding to the 

sampler at the location of highest concentration is also readily obtained. From 1996 to July 1998, air 

concentrations for only two samplers are reported, those samplers being at the point of highest air 

concentration based on monitoring in recent years. Thus, the air concentrations reported for those 

years tend to be more representative of maximum concentrations rather than site-wide averages. 

Annual air concentrations, averaged over all sampling locations, were calculated for 1995 through 

July 1998, and are listed in Table A-2. Site-wide maximum concentrations in Table A-2 correspond to 

the highest annual average concentration for any given sampler. 

For the period from August 1998 to the present, onsite air concentrations are no longer reported 

directly in the Quarterly Reports However, CDPHE reported onsite concentrations in the eastern area 

of the industrial zone, where air concentrations tended to be highest (downwind of the contaminated 

soil area) from 1999 to the present. The concentrations reported by CDPHE are used to estimate 

site-wide maximum air concentrations for the post-1998 years, and are included in Table 4-3. Special 

project monitoring is carried out to monitor specific demolition and remediation activities. Formal 

reporting of this monitoring activity is currently being requested [11].

A.3 ATMOSPHERIC TRANSPORT MODELING

The atmospheric transport modeling results used to develop estimates of 239,240Pu intake by workers 

between 1953 and 1964 relied on application of a model developed for the offsite risk assessment

(Rood and Grogan 1999) [12]. Application of this model for onsite predictions was not the original 

intent, and simulated concentrations are considered less reliable than measured concentrations for 

estimates of 239,240Pu intake for reasons stated in the introductory paragraph to this attachment. The 

application of this model for the Phase II Historical Public Exposures Studies focused on offsite rather 

than onsite concentrations, the latter being of interest here. However, the model application is such 

that building wake effects, a potential concern for areas close to the sources, are not going to be 

significant for two reasons. First, releases from the Building 771 stack are not likely to be affected by 

building wakes because the 44-m stack is sufficiently high, relative to nearby buildings, such that the 

plume is not significantly affected [13]. Second, all other elevated sources in the model were treated 

as area sources, such that initial dispersion was assigned, which implicitly accounts for the effects of 

building wakes [14].

Rood and Grogan (1999) described atmospheric transport modeling as follows (literature citations 

removed from quotation):

Atmospheric transport modeling performed in the Phase II studies used the Regional 

Atmospheric Transport Code for Hanford Environmental Tracking (RATCHET) model. Selection 

of RATCHET was based on a model comparison study performed for Phase II. In this study, five 

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models, ranging in complexity from a simple straight-line Gaussian plume model (Industrial 

Source Complex Short Term Version 2) to a complex terrain model (Terrain-Responsive 

Atmospheric Code), were compared to tracer measurements taken during the 1991 Winter 

Validation Tracer Study. The results of this evaluation indicated no one model clearly 

outperformed the others. However, the puff trajectory models (RATCHET, TRIAD, and 

INPUFF2) generally had lower variability and higher correlation to observed values compared to 

the other models. The RATCHET model was chosen for these calculations because it 

incorporates spatially varying meteorological and environmental parameters. Additionally, the 

model includes modules that perform random sampling of the meteorological parameters, 

allowing for Monte Carlo analysis of uncertainty. 

Atmospheric transport simulations were performed differently for discrete and continuous events. 

For discrete events, meteorological data for the specific days of the event were available. 

RATCHET was run using its Monte Carlo sampling features that sampled from distributions of 

basic transport parameters for each Monte Carlo trial. Transport parameters that were 

considered stochastically included wind speed, wind direction, mixing height, precipitation, and 

Monin-Obukhov scaling length. Uncertainty in the source term was also included in the 

simulation. Output consisted of n realizations of time-integrated concentration (TIC) and 

deposition at each of the 2295 computational nodes in the model domain (Figure 3). 

Continuous events were modeled somewhat differently. Meteorological data from Rocky Flats 

for most of the assessment period were lacking. Therefore, we relied on a technique often used 

in prospective analysis and in retrospective analysis when historical records are lacking. This 

technique uses compilations of recently acquired meteorological data as a surrogate for past or 

future conditions and typically only applies to assessments of long-term (>1 year) dispersion 

conditions. We employed this technique for estimating annual average plutonium concentrations 

from routine releases and continuous 903 Area suspension releases using a 5-year data set from 

1989 to 1993. Uncertainty was represented using several multiplicative correction factors that 

accounted for uncertainty in the dispersion process, meteorology, and deposition-plume 

depletion. 

The model domain (Figure 3) encompasses a 2200 km2 area (50 km north-south × 44 km eastwest). The domain extends 28 km south, 12 km west, 22 km north, and 32 km east from the 

RFP. Most of the Denver metropolitan area and the city of Boulder are included in the domain.

The domain was limited in its western extent because few receptors were present there during 

the RFP operations and most of the contaminant plumes traveled east and southeast of the 

plant.

Figure 3 from Rood and Grogan (1999) is not reproduced here because of the irrelevance of much of 

the model domain to the present study. Rather, Figure A-2 shows the model domain of relevance, 

which is the RFP industrial area. There are six nodes in the industrial area, providing the ability to 

estimate six different air concentrations for these regions. 

Discrete events in the Phase II studies were defined as those that led to releases of plutonium, which 

occurred over a relatively short period, and included releases from glovebox fires in 1957 and 1969 

and suspension of plutonium-contaminated soil from the 903 Area during unusually high-wind events 

in 1968 and 1969. Continuous releases included “routine” releases from the Building 771 stack and 

Building 776 roof vents, and suspension of 239,240Pu-contaminated soil from the 903 Area from 1964 to 

1969, before the asphalt pad was in place, but did not include the above-noted high-wind events. 

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Resuspension of 239,240Pu deposited on soil from 903 Area suspension releases and other routine and 

nonroutine events was included in the comprehensive evaluation of exposure to 239,240Pu released 

from RFP (Rood and Grogan 1999). A time-dependent factor approach was used to address the 

resuspension of soil contaminated by released 239,240Pu and deposited as a result of the continuous 

and discrete events. Rood and Grogan (1999, p. 17) describe the source term characterization. 

Aerodynamic diameter of 239,240Pu particles released is important in predicting dispersion and 

deposition and ultimately in estimating the respirable fraction of the 239,240Pu in air. The source terms 

characterized for the Phase II studies considered potential size distributions, and the predictive 

modeling addressed differential dispersion and deposition according to particle size. Thus, results of 

the modeling enabled prediction of the 239,240Pu concentration in air associated with respirable 

particles.

Comparisons of model output for the RFP onsite and perimeter regions to air monitoring data from 

onsite and perimeter samplers, respectively, were made to determine the adequacy of the predictive 

results in representing concentrations to which RFP workers might have been exposed. Figure A-3 

plots the annual average 239,240Pu concentrations in air as a function of time in the RFP industrial area 

from 1953 to 1990. Model-predicted concentrations represent the average of the six onsite 

computational nodes shown in Figure A-2, and are for particles less than 30-μm AED. Figure A-4 

plots annual average 239,240Pu concentrations in air as a function of time for the perimeter area of the 

Plant from 1953 through 1989. For perimeter locations, model-predicted concentrations represent the 

average of 27 computational nodes, shown in Figure A-5. The 5th-, 50th-, and 95th-percentile 

concentrations for 500 realizations for each of these model applications are shown for the period from 

1953 to 1989. 

Measured data shown in Figure A-3 represent the average concentrations across the onsite samplers 

listed in the legend. Samplers S-1 to S-10, S-50, and S-51 were maintained by an RFP contractor 

throughout the period of interest. The annual average TLLα data from 1965 through 1972, calculated 

from the data in Table A-1, were converted to 239,240Pu concentrations for comparison to the model 

predictions. A conversion factor of 0.36 (0.36 Ci 239,240Pu per Ci TLLα) reported in Figure III-23 in 

Rope et al. (1999) was used [15]. Average concentrations from samplers S-5 to S-9 were obtained 

from Table B-10 in Rope et al. (1999), which is reproduced in Table A-3. The onsite values in this 

table tend to be slightly higher than the averages in Table A-2 because they are restricted to samplers 

S-5 to S-9 only for all years. Figure A-3 also plots the arithmetic average of measurements obtained 

by CDPHE samplers D-3, D-4, and AP-56, located at the eastern security fence of RFP (Figure A-6). 

The data from which averages were derived for these CDPHE samplers are listed in Table A-4, which 

was reproduced from Table III-4 in Rope et al. (1999).

From Figure A-3, it is clear that the modeled 50th-percentile concentrations can underpredict the 

measured concentrations, especially after about 1970. Before 1970, agreement between model 

predictions and measured concentrations is fairly good. One possible explanation for underprediction 

that does not necessarily render modeling as an underprediction of 239,240Pu intake at RFP is that 

reported 239,240Pu concentrations are often at locations of expected elevated concentrations, while the 

modeled concentrations are averages for the entire site. After 1970, the main source of plutonium to 

onsite air was resuspension of contaminated soil (Rood and Grogan 1999, p. 57); thus, one would 

expect air concentrations in the area of highest soil plutonium (downwind of the 903 Area) to be 

higher than the site average. Because the measured data predominantly arose from that area 

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(samplers S-5 through S-9), it is likely that measured concentrations would exceed the site average. 

It is not necessarily likely, however, that an exposed individual would spend a significant amount of 

time in an area of higher 239,240Pu concentration in air. Thus, the model might be a more reasonable 

predictor of average dose for an individual exposed to average concentrations across the site, rather 

than in the areas of higher 239,240Pu concentration.

Measured data shown in Figure A-4 for the perimeter concentrations were obtained from the 1971 to 

1990 annual environmental reports prepared by RFP contractors and represent average 

concentrations from RFP contractor perimeter samplers, shown in Figure A-7 as triangular symbols. 

These data were corrected for contributions from background 239,240Pu because the measured values 

are low enough that fallout concentrations can contribute a significant portion of the total 

measurement. Yearly measurements of 239,240Pu in air in Denver (Rope et al. 1999, Table B-14, 

reproduced in Table A-5) were assumed to be representative of RFP background levels [16]. These 

levels were subtracted from the perimeter measurements in Table A-3 to obtain the average net 

perimeter 239,240Pu concentrations listed in Table A-6 and plotted in Figure A-4. From Figure A-4, it is 

clear that the model predictions and measured concentrations are in good agreement for these 

perimeter locations.

The results of these comparisons of model predictions with measured 239,240Pu concentrations support 

the following conclusions. Onsite application of the atmospheric dispersion model developed for the 

Phase II historical offsite exposure studies must be done with caution. Predicted average onsite 

concentrations might not adequately represent actual concentrations of interest due to the large 

spatial variation in soil and, thus, air contamination at the site. While it is desirable to use measured 

concentrations from the many air samplers across the site to derive average and maximum values, 

some of the historical data to support this are not readily available or of sufficient quality. Therefore, it 

is reasonable, especially before 1970, to use the Phase II model application for estimating onsite 

average concentrations in lieu of measurement data. 

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1974

1975

Figure A-1. Locations of samplers operated by RFP 

contractor. In 1975, samplers were renumbered and new 

samplers were added. (Reproduced from Rope et al. 1999, 

Figure B-6).

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479000 479500 480000 480500 481000 481500 482000 482500 483000 483500 484000 484500 485000 485500 486000

UTM Coordinate East (m)

4413000

4413500

4414000

4414500

4415000

4415500

4416000

4416500

4417000

4417500

4418000

4418500

UTM Coordinate North (m)

N

W E

S

128

Buffer zone boundary

Plant exclusion boundary

Woman Creek

North Walnut Creek

Industrial Area

Figure A-2. Location of onsite (industrial area) computational nodes (circles) used to predict average 

onsite air concentrations for RFP industrial area. 

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1950 1955 1960 1965 1970 1975 1980 1985 1990

Year

1.0x10-5

1.0x10-4

1.0x10-3

1.0x10-2

1.0x10-1

1.0x100

1.0x101

1.0x102

1.0x103

Annual Average 239,240Pu Concentration 

in Air for Particles < 30 

μm (fCi m-3)

Modeled 95th percentile

Modeled 50th percentile

Modeled 5th percentile

Average of S-1 thru S-10, S-50, and S-51 TLLa converted to 239,240Pu

Average of D-3, D-4 and AP-56

Average of S-5 - S-9

Figure A-3. Annual average 239,240Pu concentrations in air as a function of time for particles < 30-μm 

AED in RFP industrial area. [Model-predicted concentrations represent the average of six onsite 

computational nodes as shown in Figure A-3 using the model described in Rood and Grogan (1999).]

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1950 1955 1960 1965 1970 1975 1980 1985 1990

Year

1.0x10-4

1.0x10-3

1.0x10-2

1.0x10-1

1.0x100

1.0x101

1.0x102

1.0x103

Annual Average 239,240Pu Concentration 

in Air for Particles < 30 

μm (fCi m-3)

Modeled 95th percentile

Modeled 50th percentile

Modeled 5th percentile

Average of Perimeter Stations - Background

Figure A-4. Annual average 239,240Pu concentrations in air as a function of time for particles < 30-μm 

AED in the perimeter area surrounding RFP. [Model-predicted concentrations represent the average 

of 27 computational nodes as shown in Figure A-7 using the model described in Rood and Grogan 

(1999).] 

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479000 479500 480000 480500 481000 481500 482000 482500 483000 483500 484000 484500 485000 485500 486000

UTM Coordinate East (m)

4413000

4413500

4414000

4414500

4415000

4415500

4416000

4416500

4417000

4417500

4418000

4418500

UTM Coordinate North (m)

N

W E

S

128

Buffer zone boundary

Plant exclusion boundary

Woman Creek

North Walnut Creek

Industrial Area

Figure A-5. Locations of computational nodes (squares) used to compute annual average perimeter 

concentrations shown in Figure A-6. 

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Figure A-6. Eastern part of RFP industrial area, showing locations of CDPHE air monitoring 

stations D-1 to D-5. Sampler AP-56 is believed to be north of Central Avenue near the security 

fence. [Reproduced from Figure III-13 of Rope et al. (1999).]

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Figure A-7. Locations of offsite air samplers in 1975 (Figure B-4 from Rope et al. 1999). 

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Table A-1. Monthly average concentrations (fCi/m3) of total long-lived alpha activity 

in onsite air samples, October 1964 to December 1971 [reproduced from Table B-6 

in Rope et al. (1999); reconstructed from daily measurements]. Blank indicates 

sampler not in operation.

Month S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-50 S-51

Oct 64 2 6 2 4 4 3 3 11 6 4

Nov 64 1 2 6 1 2 2 2 16 3 2

Dec 64 2 3 4 2 7 4 3 79 4 3

Jan 65 2 2 11 3 7 2 2 8 3 2

Feb 65 3 2 2 4 4 4 3 4 2 3

Mar 65 5 3 3 5 3 5 2 2 3 3

Apr 65 5 3 2 2 2 3 3 5 2 2

May 65 3 13 1 3 4 5 3 4 2 3

Jun 65 4 2 2 2 4 5 2 8 2 2

Jul 65 4 2 2 2 3 6 2 9 1 3

Aug 65 4 1 2 3 3 4 2 5 2 3

Sep 65 5 3 3 3 7 5 0 5 2 4

Oct 65 3 3 3 1 2 4 2 3 3 2

Nov 65 10 3 3 2 4 4 2 9 3 4

Dec 65 4 7 7 6 14 13 5 7 4 9

Jan 66 11 6 4 2 8 4 3 12 6 14

Feb 66 3 2 3 5 6 2 1 11 3 4

Mar 66 4 2 4 3 3 3 2 11 5 3

Apr 66 3 2 3 4 4 4 2 6 3 2

May 66 4 4 4 3 6 5 5 5 7 7

Jun 66 7 5 4 2 3 13 8 12 6 8

Jul 66 7 6 4 4 6 6 5 11 7 6

Aug 66 15 7 4 12 7 11 8 13 8 6

Sep 66 28 8 9 12 18 16 5 10 7 8

Oct 66 11 4 4 7 8 8 9 10 7 4

Nov 66 7 2 3 16 8 6 6 13 5 3

Dec 66 7 4 5 14 10 12 4 8 8 6

Jan 67 8 4 7 15 13 7 6 22 23 8

Feb 67 5 6 6 22 8 8 13 38 6 4

Mar 67 6 1 5 11 7 8 5 9 5 3

Apr 67 3 3 6 6 10 7 3 11 5 7

May 67 9 4 7 8 9 12 8 9 6 5

Jun 67 10 5 8 13 14 11 17 18 5 5

Jul 67 15 5 7 8 11 14 28 19 9 3

Aug 67 27 6 15 10 11 17 28 26 10 12

Sep 67 5 3 3 6 4 14 14 22 4 5

Oct 67 5 3 7 7 5 15 24 99 7

Nov 67 6 5 10 6 4 9 8 49 7

Dec 67 9 7 17 7 3 3 9 92 4

Jan 68 8 4 12 5 6 3 8 29 5

Feb 68 15 9 23 12 7 6 10 33 11

Mar 68 14 18 22 8 9 17 11 116 28

Apr 68 16 11 13 9 6 27 31 182 10

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Table A-1 (Continued). Monthly average concentrations (fCi/m3) of total longlived alpha activity in onsite air samples, October 1964 to December 1971 

[reproduced from Table B-6 in Rope et al. (1999); reconstructed from daily 

measurements]. Blank indicates sampler not in operation.

Month S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-50 S-51

May 68 8 9 17 10 7 21 70 155 8

Jun 68 6 6 8 12 4 51 68 110 18

Jul 68 5 4 7 4 4 14 14 31 3

Aug 68 9 6 8 5 7 9 10 17 4

Sep 68 6 6 7 5 5 4 9 50 3

Oct 68 12 7 8 6 4 11 19 33 3 7 11

Nov 68 7 4 6 3 7 9 6 168 4 4 2

Dec 68 11 6 4 8 6 6 20 357 3 11 3

Jan 69 10 6 9 7 10 15 127 1525 3 7 5

Feb 69 6 4 8 5 5 4 23 129 3 4 3

Mar 69 7 4 3 5 4 2 4 208 2 5 3

Apr 69 7 3 5 3 6 3 22 148 4 4 5 6

May 69 5 11 9 9 9 17 21 28 10 6 9 6

Jun 69 4 4 7 4 4 7 9 68 4 4 7 3

Jul 69 15 7 7 7 4 20 7 20 4 4 11 6

Aug 69 4 6 5 6 5 7 7 22 5 3 6 9

Sep 69 6 6 5 5 6 5 6 19 4 3 5 5

Oct 69 6 3 5 18 3 5 3 12 2 3 3 3

Nov 69 3 2 4 5 4 3 2 12 2 3 4 4

Dec 69 5 4 5 7 4 2 4 32 7 5 4 4

Jan 70 3 2 4 4 4 3 3 12 3 4 2 3

Feb 70 2 4 5 4 3 4 13 33 3 6 2 7

Mar 70 3 4 4 15 3 5 4 10 4 4 3 5

Apr 70 10 5 5 7 9 7 5 7 2 3 5 3

May 70 9 4 5 3 4 4 2 10 1 4 4 4

Jun 70 14 7 12 9 57 13 7 10 4 13 7 10

Jul 70 7 5 1 3 2 2 2 4 3 3 4 4

Aug 70 3 4 2 3 2 4 10 4 3 4 2 5

Sep 70 2 6 6 3 3 3 3 5 3 4 4 4

Oct 70 5 3 5 4 3 4 2 5 3 4 3 4

Nov 70 2 6 3 3 5 4 1 3 2 2 4 2

Dec 70 3 4 3 3 3 3 6 5 2 3 4 2

Jan 71 4 4 3 2 3 4 7 5 4 4 4 4

Feb 71 3 4 2 4 4 3 6 7 4 5 3 5

Mar 71 5 4 4 5 3 3 8 8 4 5 8 4

Apr 71 4 4 5 7 4 3 3 26 4 5 5 5

May 71 5 4 5 3 4 6 4 9 4 5 5 4

Jun 71 4 3 4 5 5 4 4 10 4 7 7 4

Jul 71 4 3 5 4 4 12 3 12 3 2 4 2

Aug 71 4 4 6 4 3 3 4 8 4 3 9 4

Sep 71 5 3 6 3 3 3 2 6 3 4 6 3

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Table A-1 (Continued). Monthly average concentrations (fCi/m3) of total longlived alpha activity in onsite air samples, October 1964 to December 1971 

[reproduced from Table B-6 in Rope et al. (1999); reconstructed from daily 

measurements].

Month S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-50 S-51

Oct 71 5 4 4 3 6 3 2 12 2 5 7 5

Nov 71 3 4 6 3 5 5 3 10 2 4 5 4

Dec 71 4 5 4 3 3 4 4 6 3 4 5 4

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Table A-2. Estimated annual average concentrations (fCi/m3) of 239,240Pu in onsite air samples 

between 1965 and 1994a based on measurement data provided in Table A-1, RFP annual 

environmental reports, RFETS monthly and quarterly monitoring reports, and CDPHE quarterly 

environmental surveillance reports. 

Year Sampling locationb

Type of 

measurement

Conversion 

factor to 

239,240Puc

Annual average 

air concentration 

(fCi/m3)

Maximum air 

concentrationd

(fCi/m3)

1965 S1-S10 TLLα 0.36 1e 2e

1966 S1-S10 TLLα 0.36 2e 4e

1967 S1-S10 TLLα 0.36 4e 12e

1968 S1-S8, S10 TLLα 0.36 7e 38e

1969 S1-S10, S50-S51 TLLα 0.36 8e 67e

1970 S1-S10, S50-S51 TLLα 0.36 2e 3e

1971 S1-S10, S50-S51 TLLα 0.36 2e 4e

1972 S1-S10, S50-S51 TLLα 0.36 <2.1 3.9

1973 S1-S10, S50-S52 TLLα 0.36 <2.2 <3.9

1973 S1-S10, S50-S52 Pu-239,240 1 <1.2 <6.5

1974 S1-S10, S50-S52 Pu-239,240 1 0.6 3.2

1975 S1-S10, S22, S50-S52, Af83, Ac84 Pu-239,240 1 <0.2 1.0

1976 S1-S24 Pu-239,240 1 0.2 1.4

1977 S1-S24 Pu-239,240 1 0.3f 0.6

1978 S5-S9, S19-S21 Pu-239,240 1 0.3f 0.9

1979 S2, S5-S9,S15-S16, S19-S21 Pu-239,240 1 0.2f 0.5

1980 S5-S9, S16, S19-S21 Pu-239,240 1 0.2f 0.5

1981 S5-S9, S16, S19-S21 Pu-239,240 1 0.2f 0.5

1982 S5-S9, S16, S19-S21 Pu-239,240 1 0.3f.g 0.5

1983 S5-S9 Pu-239,240 1 0.2f.g 0.4

1984 S5-S9 Pu-239,240 1 0.3f.g 0.6

1985 S5-S9 Pu-239,240 1 0.2f.g 0.4

1986 S5-S9 Pu-239,240 1 0.3f.g 0.5

1987 S5-S9 Pu-239,240 1 0.7f.g 1.2

1988 S5-S9 Pu-239,240 1 0.5f.g 0.7

1989 S5-S9 Pu-239,240 1 0.4 0.5

1990 S1-S24, S88 Pu-239,240 1 0.1 0.9

1991 S1-S25 Pu-239,240 1 0.1 1.2

1992 S1-S25 Pu-239,240 1 0.1 0.6

1993 S3-S25 Pu-239,240 1 0.1 0.4

1994 S3-S25 Pu-239,240 1 0.1 0.4

1995h S005–S007, S009, S101-104, S106, S107, S109, S110, S112, 

S116, S119, S121, S123, S202–S206, S208, S211

Pu-239,240 1 0.02 0.2

1996h S007, S107 Pu-239,240 1 0.08 0.08

1997h S007, S107 Pu-239,240 1 0.05 0.07

1998h,i S007, S107 Pu-239,240 1 0.080 0.1

1999j,k D-1,D-3 Pu-239,240 1 0.07 0.1

2000j D-1,D-3 Pu-239,240 1 0.08 0.1

2001j D-1,D-3 Pu-239,240 1 0.08 0.2

2002j D-1,D-3 Pu-239,240 1 0.03 0.05

2003j D-1,D-3 Pu-239,240 1 0.09 0.2

2004j D-1 Pu-239,240 1 0.03 0.03

2005j,l D-1 Pu-239,240 1 0.1 0.1

a. Compiled from measurement data in Dow (1972a, 1973 to 1975); Rockwell (1976 to 1989); EG&G (1989 to 1993); and Kaiser-Hill (1994), unless otherwise 

noted. 

b. Refer to Figure A-1 for samplers through 1994; after 1994, see monthly and quarterly monitoring reports for maps.

c. Based on Rope et al. (1999, pp. III-42 – III-46).

d. The maximum monthly concentration at any one sampling location.

e. Calculated from data in Table A-1.

f. Calculated by averaging reported annual volume-weighted average concentration for each sampler.

g. Results only reported for samplers in area of higher measured plutonium air concentrations for RFP.

h. From RFETS quarterly environmental monitoring reports (RFETS 1995a,b,c, 1996a,b,c, 1998a,b). 

i. Based on data collected January through July 1998.

j. From CDPHE quarterly environmental surveillance reports (CDPHE 2000 to 2005b). 

k. Based on last 3 quarters only.

l. Based on first 2 quarters only.

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Table A-3. Annual average concentrations (fCi-m3) of 

plutonium in air for three location groups, RFP contractor 

monitoring, 1971 to 1990a [reproduced from Table B-10 in 

Rope et al. (1999)]. Blank indicates no sampler.

Year Onsiteb Perimeter Community

1971 0.26

1972 0.14

1973 0.274 0.05 0.26

1974 0.892 0.058 0.34

1975 0.517 0.037 0.031

1976 0.698 0.015 0.013

1977 0.393 0.038 0.037

1978 0.446 0.06 0.06

1979 0.278 0.02 0.02

1980 0.252 0.01 0.01

1981 0.287 0.018 0.019

1982 0.244 0.005 0.006

1983 0.226 0.003 0.007

1984 0.257 0.005 0.005

1985 0.235 0.002 0.002

1986 0.225 0.005 0.003

1987 0.639 0.005 0.003

1988 0.529 0.003 0.002

1989 0.363 0.001 0.001

1990 0.102 0.002 0.001

a. Obtained from RFP contractor annual reports. Data are plotted as a line 

chart in Rope et al. (1999, Chapter III). 

b. Onsite samples are the average of locations S–5, S–6, S–7, S–8, and 

S–9, as numbered in 1975. 

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Table A-4. Data from Table III-4 in Rope et al. (1999) showing a comparison of 239,240Pu

concentrations (fCi/m3

) in onsite and offsite air, measured by CDPHE. Blank – no data.

Location 1969 1970 1971 1972 1973 1974

Onsite

D-1 0.29 0.31 1.44 0.74 0.44

D-2 0.37 0.34 0.69 0.62 0.73

D-3 6.29 10.29 4.47 2.87 3.77

D-4 2.21 7.34 5.48 4.63 1.33

APC-56 2.73 1.25 1.77 2.28 0.28 0.43

 Onsite averagea 2.73 2.08 4.01 2.87 1.83 1.34

Offsite (metro):

D-5 (SE boundary) 0.16 0.13 0.12 0.10 0.10

APC-2 Denver (EPA data)b 0.070 0.077 0.066 0.040 0.015 0.049

APC-15 Arvada 0.16 <0.08 0.06 <0.06 0.25

APC-16 Golden 0.08 <0.11 0.08 <0.06 <0.06 <0.08

APC-19 Boulder 0.13 <0.07 <0.05 <0.06 <0.06

APC-22 Longmont 0.08 0.12 0.07 <0.02 <0.05 <0.1

 Offsite (metro) averagea 0.08 0.13 0.08 0.06 0.06 0.12

Offsite (remote):

APC-29 Durango <0.12 <0.02 <0.05

APC-42 Fort Collins <0.04 <0.08 0.14

APC-81 Walsenburg 0.07 <0.06 0.38

APC-108 Rangely 0.1 <0.08 0.13

 Offsite (remote) averageb 0.08 0.06 0.18

a. Averages in this table are arithmetic averages of the annual averages from each station. 

b. Lower minimum detectable concentration for EPA data (0.001 compared to 0.08 for APC-x stations and 

0.03 for D-x stations).

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Table A-5. Data from Table B-14 in Rope et al. (1999) showing annual 

average concentrations (fCi/m3

) of 239,240Pu in Denver air, 1971 to 1989. 

Year Average 5th percentile 95th percentile Method of determinationa

1971 6.6E-2 5.3E-2 7.9E-2 M

1972 4.0E-2 3.2E-2 4.8E-2 M

1973 1.5E-2 1.2E-2 1.8E-2 M

1974 4.9E-2 3.9E-2 5.9E-2 M

1975 3.1E-2 2.5E-2 3.7E-2 M

1976 1.1E-2 9.0E-3 1.3E-2 M

1977 3.6E-2 2.8E-2 4.0E-2 M

1978 4.8E-2 3.8E-2 5.7E-2 M

1979 1.2E-2 9.3E-3 1.4E-2 M

1980 7.6E-3 3.8E-3 1.1E-2 M

1981 1.6E-2 3.8E-3 1.1E-2 N

1982 2.3E-3 8.0E-3 2.4E-2 N

1983 1.3E-3 6.5E-4 2.0E-3 M

1984 1.0E-3 5.0E-4 1.5E-3 M

1985 4.0E-3 2.3E-3 6.8E-3 M

1986 2.5E-3 1.2E-3 3.7E-3 M

1987 6.0E-4 3.0E-4 9.0E-4 M

1988 1.0E-4 5.0E-5 1.5E-4 M

1989 7.0E-4 3.5E-4 1.0E-3 M

a. M = average of values measured by the Public Health Service or EPA in Denver for that 

year. See Figure III-7 and associated text in Rope et al. (1999) for additional discussion.

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Table A-6. Corrected annual average concentrations of 

239,240Pu in air at perimeter monitoring stations (from Table 

B-10 in Rope et al. 1999).

Year

Pu-239, -240

concentration (fCi/m3)

a Net Pu-239, -240

concentration (fCi/m3)

b

1971 2.60E-01 1.94E-01

1972 1.40E-01 1.00E-01

1973 5.00E-02 3.50E-02

1974 5.80E-02 9.00E-03

1975 3.70E-02 6.00E-03

1976 1.50E-02 4.00E-03

1977 3.80E-02 2.00E-03

1978 6.00E-02 1.20E-02

1979 2.00E-02 8.00E-03

1980 1.00E-02 2.40E-03

1981 1.80E-02 2.00E-03

1982 5.00E-03 2.70E-03

1983 3.00E-03 1.70E-03

1984 5.00E-03 4.00E-03

1985 2.00E-03 0.00E+00c

1986 5.00E-03 2.50E-03

1987 5.00E-03 4.40E-03

1988 3.00E-03 2.90E-03

1989 1.00E-03 3.00E-04

1990 2.00E-03 2.00E-03

a. From Table A-3.

b. The net concentration is the concentration in the second column minus 

the corresponding average background value reported in Table A-5. 

c. Average background measurement (Table A-5) exceeded measured 

perimeter value.

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TABLE OF CONTENTS 

SECTION TITLE

B.1 Screening Methodology ........................................................................................................

PAGE

56

B.2 Tritium....................................................................................................................................56

B.3 Depleted and Enriched Uranium ............................................................................................ 57

B.4 Americium-241.......................................................................................................................58

LIST OF TABLES

TABLE TITLE

B-1 Maximum estimated committed doses for tritium by year .......................................................

PAGE

59

B-2 Maximum estimated committed doses for depleted uranium, by year..................................... 60

B-3 Maximum estimated committed doses for enriched uranium by year ..................................... 61

B-4 Maximum estimated committed doses for 241Am by year........................................................ 62

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B.1 SCREENING METHODOLOGY 

To evaluate the potential importance of the radionuclides other than plutonium isotopes reported to 

have been released to the air at RFP since operations began in 1952, information from Phase I and 

Phase II of the Historical Public Exposure Studies on RFP (ChemRisk 1994a; Rood and Grogan 

1999) were used to estimate maximum historical onsite yearly inhalation doses for the radionuclides 

identified. Radionuclides were considered insignificant contributors to dose if estimated maximum 

committed dose for a 1-yr intake associated with the release was on the order of 1 mrem or less for 

the period of interest [17].

The source terms described in Phase I were assumed to be reasonable estimates of the releases of 

tritium, depleted uranium, enriched uranium, and 241Am [18]. For Phase I, effluent monitoring data 

reported by RFP was reviewed and determined to provide a good basis for estimating airborne 

releases of all radionuclides with the exception of believed under-reporting of uranium emissions prior 

to 1961 (ChemRisk 1994a, p. 9). Emissions for uranium were reconstructed from raw data found in 

logbooks in the Denver Federal Records Center (ChemRisk 1994a, p. 75). For the period before 

1978, “total long-lived alpha radioactivity measured from facilities which process depleted uranium 

was assumed to represent depleted uranium and total long-lived alpha radioactivity measured from 

facilities which process enriched uranium was assumed to represent enriched uranium” (ChemRisk 

1994a, p. 113). It is important to note that the release estimates reported here do not appear to 

include emissions from the 903 Area, which occur as a result of suspension of the primary 

contamination (i.e., oil-contaminated soil), or resuspension of the windblown material deposited 

downwind. Thus, this component of the emissions of 241Am is not fully evaluated here, and is 

addressed in the Occupational Environmental Dose section. 

To calculate an estimated maximum committed dose for a 1-yr intake from these releases, the 95thpercentile release rates were multiplied by the maximum predicted normalized air concentration (χ/Q), 

in s/m3

, to obtain the maximum onsite air concentration for each radionuclide. The χ/Q value was 

obtained from atmospheric dispersion modeling done in Phase II Comprehensive Assessment of 

Exposure and Lifetime Cancer Incidence Risk from Plutonium Released from the Rocky Flats Plant, 

1953-1989 (Rood and Grogan 1999), where all identified sources of plutonium were considered 

together to develop plutonium air concentration profiles of the RFP vicinity. The maximum χ/Q value 

for the industrial area and buffer zone was selected for estimating annual air concentrations. The 

model predicted a maximum χ/Q of 6.28 × 10-6 s/m3 at a computational node in the north-central 

portion of the industrial area of the site.

Calculated annual air concentrations were multiplied by an inhalation rate of 2,400 m3

/yr, representing 

a 2,000-hr work year and 1.2 m3

/hr inhalation rate to obtain an estimate of annual radionuclide intake. 

The maximum annual intake for each radionuclide was multiplied by its respective inhalation dose 

factor from ICRP Publication 68 to obtain an estimate of maximum committed dose for a 1-yr intake

(ICRP 2001). 

B.2 TRITIUM

Tritium is known to have been released during routine RFP operations and accidents. Routine 

releases were reported in annual reports after 1973 (ChemRisk 1994b) and were estimated to be less 

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than 10 Ci/yr. Several larger releases of tritium were documented and reviewed in the Phase I study. 

The three most significant incidents with respect to tritium release occurred in 1968, 1973, and 1974. 

The highest estimated release of tritium cited in the Phase I study occurred in the 1973 accident, 

where it was reported that as much as 350 to 1,600 Ci of tritium were released in exhausted air from 

Building 779A. 

The estimated annual releases (Q) of tritium, in curies per year, from the Phase I study are listed in 

Table B-1. This table includes the inhalation dose factor assumed for tritium (ICRP 2001) and the 

calculated dose for each year. (Note: All tables appear at the end of this attachment.) For screening 

purposes, this inhalation factor corresponds to the highest value reported for all forms of tritium 

compounds (ICRP 2001), representing inhalation of organically bound tritium compounds, and is 

approximately 2.3 times higher than the value for tritiated water vapor. While this is clearly an 

overestimate of the dose factor for the most likely form of tritium (water vapor), it was chosen to offset 

the uncertainty in the χ/Q value used, which might not accurately estimate the true normalized air 

concentration for tritiated water vapor because it assumes the emitted compounds are particulate. 

Dry deposition of tritium is not like that of other radiological species due to its association with water 

vapor (O’Kula and Murphy 2001). From Table B-1, the maximum dose was calculated for 1953 to 

1989 to be less than 1 mrem/yr. Thus, tritium was an insignificant contributor to inhalation dose 

based on the criterion put forth in the first paragraph of this attachment, and is not addressed further 

in this TBD.

B.3 DEPLETED AND ENRICHED URANIUM

Uranium was processed at RFP in two forms: depleted and enriched. Release estimates in the 

Phase I studies (ChemRisk 1994b) were developed for both forms. Until 1978, estimated release of 

both forms rely on measurements of TLLα because routine isotopic analyses of effluent sample filters 

from uranium facilities were not performed until that time. After 1978, not all uranium isotopes of 

interest were routinely measured. Thus, the Phase I analysis based estimates on known alpha 

activity fractions for the two types of uranium. 

Approximately 15 mCi of depleted uranium and 7 mCi of enriched uranium were released to the RFP 

air environment between 1953 and 1989. According to the ChemRisk (1994b) analysis, more than 

90% of the activity released is estimated to have occurred before 1970, with the highest releases in 

the 1950s. 

The estimated annual releases (Q) of depleted and enriched uranium, in microcuries per year, from 

the Phase I study are listed in Tables B-2 and B-3. These tables include the inhalation dose factor 

assumed for the two forms of uranium and the calculated doses for each year. The dose factor used 

is the maximum dose factor associated with airborne particulate uranium isotopes (i.e., that for 0.3-μm 

AMAD 234U, of absorption type S) included in depleted and enriched uranium, and applies to the organ 

receiving the highest dose (lungs). From Tables B-2 and B-3, the maximum doses calculated for 

1953 to 1989 for both forms of uranium were always less than 1 mrem/yr with one exception. In 1955, 

a maximum dose of 1.2 mrem is predicted for depleted uranium. In light of the dose-maximizing 

assumptions made in these calculations, it is not expected that intakes of released depleted or 

enriched uranium realistically exceeded 1 mrem/yr; thus, depleted and enriched uranium were 

considered insignificant contributors to inhalation dose and are not addressed further in this TBD. 

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This conclusion is supported by the conclusions of the analysis by Voillequé (1999d) in the Phase II 

study, which found that releases of enriched and depleted uranium at RFP pose substantially less risk 

(in terms of radiological dose) than plutonium releases.

B.4 AMERICIUM-241 

Americium-241, a decay product of 241Pu, exists as an undesirable contaminant in weapons-grade 

plutonium. Although RFP plutonium initially contained about 0.0001% 241Am (ChemRisk 1994b, 

p. 106), the 241Am-to239/240Pu ratio increases over time due to decay of 241Pu. Not until 1985 were 

241Am effluents routinely monitored at RFP. Thus, an estimate of the release rate of this isotope from 

all possible sources requires assumptions regarding the ratio of its activity to other alpha emitters for 

which activity was measured. Based on data for 1985 to 1989, the average ratio of 241Am-to239/240Pu 

emissions was about 22% (ChemRisk 1994b, p. 110). Therefore, the Phase I work assumed that this 

ratio existed throughout the entire operational period of the facility to derive estimated releases of 

241Am, in microcuries per year, listed in Table B-4. This assumption might not be realistic if efforts 

were made to separate the 241Am from the plutonium being processed, but it is likely more applicable 

to resuspension releases of this isotope that occur years after the plutonium was deposited on the 

soil.

Table B-4 estimates show peak 241Am releases occurring in 1957 (because the peak 239/240Pu releases 

occurred during that year from the 1957 fire) and dropping off dramatically since 1976. A total of 

11 mCi is calculated to have been released, with 34% of that in 1957. 

Table B-4 includes the inhalation dose factor assumed for 241Am (ICRP 2001) and the calculated dose 

for each year. The inhalation dose factor was maximized by assuming a particulate AMAD of 0.3 μm, 

absorption type M, and the organ receiving the highest dose (bone surfaces). From Table B-4, the 

maximum dose was calculated for 1953 to 1989 to be approximately 34 mrem/yr in 1957. Thus, 

241Am was considered a potentially significant contributor to inhalation dose based on the criterion in 

the first paragraph of this attachment, and is addressed as such in this TBD.

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Table B-1. Maximum estimated committed doses for tritium by year. 

Year

Annual tritium releasea 95% CL calculated 

air concentrationb (μCi/m3)

Maximum tritium 

dosec GM (Ci/yr) 95% CL (Ci/yr) (mrem/yr)

1953 NA 8.00E+02 1.59E-04 5.8E-02

1954 NA 8.00E+02 1.59E-04 5.8E-02

1955 NA 8.00E+02 1.59E-04 5.8E-02

1956 NA 8.00E+02 1.59E-04 5.8E-02

1957 NA 8.00E+02 1.59E-04 5.8E-02

1958 NA 8.00E+02 1.59E-04 5.8E-02

1959 NA 8.00E+02 1.59E-04 5.8E-02

1960 NA 8.00E+02 1.59E-04 5.8E-02

1961 NA 8.00E+02 1.59E-04 5.8E-02

1962 NA 8.00E+02 1.59E-04 5.8E-02

1963 NA 8.00E+02 1.59E-04 5.8E-02

1964 NA 8.00E+02 1.59E-04 5.8E-02

1965 NA 8.00E+02 1.59E-04 5.8E-02

1966 NA 8.00E+02 1.59E-04 5.8E-02

1967 NA 8.00E+02 1.59E-04 5.8E-02

1968 NA 3.90E+02 7.76E-05 5.8E-02

1969 NA 3.90E+02 7.76E-05 2.8E-02

1970 NA 3.90E+02 7.76E-05 2.8E-02

1971 NA 3.90E+02 7.76E-05 2.8E-02

1972 NA 3.90E+02 7.76E-05 2.8E-02

1973 NA 3.90E+02 7.76E-05 2.8E-02

1974 2.50E+01 5.70E+01 1.13E-05 2.8E-02

1975 3.90E+00 8.80E+00 1.75E-06 4.1E-03

1976 3.10E+00 7.00E+00 1.39E-06 6.4E-04

1977 1.40E+00 3.10E+00 6.17E-07 5.1E-04

1978 2.30E+00 5.30E+00 1.06E-06 2.2E-04

1979 2.20E+00 4.90E+00 9.75E-07 3.8E-04

1980 2.00E+00 4.60E+00 9.16E-07 3.6E-04

1981 1.10E+00 2.60E+00 5.18E-07 3.3E-04

1982 6.00E-01 1.40E+00 2.79E-07 1.9E-04

1983 4.20E-01 9.40E-01 1.87E-07 1.0E-04

1984 3.60E-01 8.20E-01 1.63E-07 6.8E-05

1985 4.20E-01 9.40E-01 1.87E-07 5.9E-05

1986 5.70E-01 1.30E+00 2.59E-07 6.8E-05

1987 4.40E-01 9.90E-01 1.97E-07 9.4E-05

1988 6.80E-02 1.50E-01 2.99E-08 7.2E-05

1989 4.40E-01 9.90E-01 1.97E-07 1.1E-05

a. From Phase I studies (ChemRisk 1994b). 

b. Based on maximum χ/Q of 6.28 × 10-6 s/m3

. 

c. Assuming dose factor of 1.52 × 10-1 mrem/μCi and intake rate of 2,400 m3

/yr. 

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Table B-2. Maximum estimated committed doses for depleted uranium, by year. 

Year

Annual depleted uranium releasea 95% CL calculated 

air concentrationb (μCi/m3)

Maximum depleted 

uranium dosec GM (μCi/yr) 95% CL (μCi/yr) (mrem/yr)

1953 1.60E+03 4.00E+03 7.96E-10 7.0E-01

1954 1.60E+03 4.00E+03 7.96E-10 7.0E-01

1955 2.70E+03 7.00E+03 1.39E-09 1.2E+00

1956 1.30E+03 3.30E+03 6.57E-10 5.8E-01

1957 9.50E+02 2.40E+03 4.78E-10 4.2E-01

1958 2.10E+03 5.30E+03 1.06E-09 9.3E-01

1959 3.50E+02 9.00E+02 1.79E-10 1.6E-01

1960 4.60E+02 1.20E+03 2.39E-10 2.1E-01

1961 6.80E+02 1.70E+03 3.38E-10 3.0E-01

1962 4.80E+02 1.20E+03 2.39E-10 2.1E-01

1963 6.40E+02 1.60E+03 3.19E-10 2.8E-01

1964 3.10E+02 8.00E+02 1.59E-10 1.4E-01

1965 3.60E+02 9.30E+02 1.85E-10 1.6E-01

1966 1.80E+02 4.70E+02 9.36E-11 8.2E-02

1967 1.80E+02 4.70E+02 9.36E-11 8.2E-02

1968 1.80E+02 4.70E+02 9.36E-11 8.2E-02

1969 2.10E+02 5.30E+02 1.06E-10 9.3E-02

1970 2.50E+02 6.30E+02 1.25E-10 1.1E-01

1971 7.50E+01 1.90E+02 3.78E-11 3.3E-02

1972 5.50E+01 1.40E+02 2.79E-11 2.4E-02

1973 7.00E+01 1.80E+02 3.58E-11 3.1E-02

1974 1.20E+01 3.00E+01 5.97E-12 5.2E-03

1975 3.60E+01 9.30E+01 1.85E-11 1.6E-02

1976 1.60E+01 4.00E+01 7.96E-12 7.0E-03

1977 2.50E+01 6.30E+01 1.25E-11 1.1E-02

1978 4.30E+01 1.10E+02 2.19E-11 1.9E-02

1979 3.40E+01 8.70E+01 1.73E-11 1.5E-02

1980 2.00E+01 5.00E+01 9.95E-12 8.7E-03

1981 2.30E+01 6.00E+01 1.19E-11 1.0E-02

1982 2.50E+01 6.30E+01 1.25E-11 1.1E-02

1983 4.00E+01 1.00E+02 1.99E-11 1.7E-02

1984 7.20E+00 1.80E+01 3.58E-12 3.1E-03

1985 5.10E+01 1.30E+02 2.59E-11 2.3E-02

1986 3.80E+00 9.70E+00 1.93E-12 1.7E-03

1987 1.60E+01 4.00E+01 7.96E-12 7.0E-03

1988 1.20E+01 3.10E+01 6.17E-12 5.4E-03

1989 3.30E+00 8.30E+00 1.65E-12 1.5E-03

a. From Phase I studies (ChemRisk 1994b). 

b. Based on maximum χ/Q of 6.28 × 10-6 s/m3

. 

c. Assuming U-234 organ dose factor of 3.66 × 105 mrem/μCi and intake rate of 2,400 m3

/yr. 

ATTACHMENT B

SCREENING OF RADIONUCLIDE SOURCE TERMS 

FOR ENVIRONMENTAL DOSE EVALUATION

Page 6 of 8 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 61 of 62

Table B-3. Maximum estimated committed doses for enriched uranium by year. 

Year

Annual enriched uranium releasea 95% CL calculated 

air concentrationb (μCi/m3)

Maximum enriched 

uranium dosec GM (μCi/yr) 95% CL (μCi/yr) (mrem/yr)

1953 1.20E+01 3.00E+01 5.97E-12 5.2E-03

1954 1.20E+01 3.00E+01 5.97E-12 5.2E-03

1955 9.60E+01 2.50E+02 4.98E-11 4.4E-02

1956 1.40E+03 3.70E+03 7.37E-10 6.5E-01

1957 4.70E+02 1.20E+03 2.39E-10 2.1E-01

1958 4.00E+02 1.00E+03 1.99E-10 1.7E-01

1959 7.00E+02 1.80E+03 3.58E-10 3.1E-01

1960 1.10E+03 2.90E+03 5.77E-10 5.1E-01

1961 6.20E+02 1.60E+03 3.19E-10 2.8E-01

1962 3.20E+02 8.30E+02 1.65E-10 1.5E-01

1963 4.30E+02 1.10E+03 2.19E-10 1.9E-01

1964 2.50E+02 6.30E+02 1.25E-10 1.1E-01

1965 2.50E+02 6.30E+02 1.25E-10 1.1E-01

1966 3.00E+02 7.70E+02 1.53E-10 1.3E-01

1967 1.40E+02 3.70E+02 7.37E-11 6.5E-02

1968 2.10E+02 5.30E+02 1.06E-10 9.3E-02

1969 6.50E+01 1.70E+02 3.38E-11 3.0E-02

1970 8.30E+01 2.10E+02 4.18E-11 3.7E-02

1971 5.30E+01 1.40E+02 2.79E-11 2.4E-02

1972 5.20E+00 1.30E+01 2.59E-12 2.3E-03

1973 1.60E+01 4.00E+01 7.96E-12 7.0E-03

1974 3.50E+01 9.00E+01 1.79E-11 1.6E-02

1975 3.60E+01 9.30E+01 1.85E-11 1.6E-02

1976 2.10E+01 5.30E+01 1.06E-11 9.3E-03

1977 2.70E+01 7.00E+01 1.39E-11 1.2E-02

1978 2.70E+01 7.00E+01 1.39E-11 1.2E-02

1979 1.20E+01 3.10E+01 6.17E-12 5.4E-03

1980 2.00E+01 5.00E+01 9.95E-12 8.7E-03

1981 1.60E+01 4.00E+01 7.96E-12 7.0E-03

1982 1.60E+01 4.00E+01 7.96E-12 7.0E-03

1983 2.60E+01 6.70E+01 1.33E-11 1.2E-02

1984 2.60E+01 6.70E+01 1.33E-11 1.2E-02

1985 1.00E+01 2.60E+01 5.18E-12 4.5E-03

1986 1.40E+01 3.70E+01 7.37E-12 6.5E-03

1987 6.00E+00 1.50E+01 2.99E-12 2.6E-03

1988 3.40E+00 8.70E+00 1.73E-12 1.5E-03

1989 6.80E+00 1.70E+01 3.38E-12 3.0E-03

a. From Phase I studies (ChemRisk 1994b). 

b. Based on maximum χ/Q of 6.28 × 10-6 s/m3

. 

c. Assuming U-234 organ dose factor of 3.66 × 105 mrem/μCi and intake rate of 2,400 m3

/yr. 

ATTACHMENT B

SCREENING OF RADIONUCLIDE SOURCE TERMS 

FOR ENVIRONMENTAL DOSE EVALUATION

Page 7 of 8 
Document No. ORAUT-TKBS-0011-4 Revision No. 02 Effective Date: 04/23/2007 Page 62 of 62

Table B-4. Maximum estimated committed doses for 241Am by year. 

Year

Annual Am-241 releasea 95% CL calculated 

air concentrationb (μCi/m3)

Maximum Am-241 

dosec GM (μCi/yr) 95% CL (μCi/yr) (mrem/yr)

1953 5.00E-01 1.30E+00 2.59E-13 4.6E-03

1954 1.70E+01 4.30E+01 8.56E-12 1.5E-01

1955 1.80E+01 4.70E+01 9.36E-12 1.7E-01

1956 5.70E+01 1.50E+02 2.99E-11 5.3E-01

1957 3.80E+03 9.70E+03 1.93E-09 3.4E+01

1958 7.80E+02 2.00E+03 3.98E-10 7.1E+00

1959 3.50E+02 9.00E+02 1.79E-10 3.2E+00

1960 3.20E+02 8.20E+02 1.63E-10 2.9E+00

1961 3.80E+02 9.70E+02 1.93E-10 3.4E+00

1962 7.60E+02 1.90E+03 3.78E-10 6.7E+00

1963 9.10E+02 2.30E+03 4.58E-10 8.1E+00

1964 7.00E+02 1.80E+03 3.58E-10 6.4E+00

1965 1.70E+03 4.30E+03 8.56E-10 1.5E+01

1966 8.10E+01 2.10E+02 4.18E-11 7.4E-01

1967 1.00E+02 2.60E+02 5.18E-11 9.2E-01

1968 1.20E+02 3.20E+02 6.37E-11 1.1E+00

1969 3.50E+02 9.00E+02 1.79E-10 3.2E+00

1970 9.50E+01 2.40E+02 4.78E-11 8.5E-01

1971 1.80E+01 4.70E+01 9.36E-12 1.7E-01

1972 1.50E+01 3.90E+01 7.76E-12 1.4E-01

1973 1.50E+01 3.90E+01 7.76E-12 1.4E-01

1974 2.90E+02 7.50E+02 1.49E-10 2.7E+00

1975 3.10E+01 7.90E+01 1.57E-11 2.8E-01

1976 1.20E+00 3.20E+00 6.37E-13 1.1E-02

1977 1.20E+00 3.20E+00 6.37E-13 1.1E-02

1978 8.70E-01 2.20E+00 4.38E-13 7.8E-03

1979 1.70E+00 4.30E+00 8.56E-13 1.5E-02

1980 3.60E+00 9.30E+00 1.85E-12 3.3E-02

1981 2.50E+00 6.50E+00 1.29E-12 2.3E-02

1982 6.20E+00 1.60E+01 3.19E-12 5.7E-02

1983 2.40E+01 6.10E+01 1.21E-11 2.2E-01

1984 2.40E+01 6.10E+01 1.21E-11 2.2E-01

1985 2.80E+00 7.20E+00 1.43E-12 2.5E-02

1986 1.30E+01 3.30E+01 6.57E-12 1.2E-01

1987 4.50E+00 1.20E+01 2.39E-12 4.2E-02

1988 2.80E+00 7.20E+00 1.43E-12 2.5E-02

1989 1.50E+00 3.90E+00 7.76E-13 1.4E-02

a. From Phase I studies (ChemRisk 1994b). 

b. Based on maximum χ/Q of 6.28 × 10-6 s/m3

. 

c. Assuming organ dose factor of 7.40 × 106 mrem/μCi and intake rate of 2,400 m3

/yr.

ATTACHMENT B

SCREENING OF RADIONUCLIDE SOURCE TERMS 

FOR ENVIRONMENTAL DOSE EVALUATION

Page 8 of 8